Every character in a fictional work will always have a skill. These skills can be anything like choosing the right people for a job, stealth, pickpocketing and so on. Normally, a skill has to be learned, and once a character learns it, s/he has to practice it lest s/he forgets how to do it.
Not these skills. These skills are learned once, and then the character never forgets how to do them, even if s/he hasn't used them for years.
There is a Stock Phrase representing this trope called "Like riding a bicycle/bike" as well as the phrase "An elephant never forgets". However, the page is not about either stock phrase. On an interesting side note, Russia has an equivalent phrase that says "мастерство не пропьёшь" (masterstvo ne propʹyošʹ), which literally translates to "mastery (you can) not drink away". As laugh-inducing as that may sound, any skill that doesn't go away due to alcohol has to qualify for this trope.
This is pretty much the default situation in Tabletop Games that use skills. It is very rare for an RPG's rules to have characters lose skills even when they're not used for long periods of time. By extension, there are so many examples of this trope in Video Games that it would be easier to list the video games that subvert or avert this trope.
This trope can result in Damn You, Muscle Memory!. Bag of Spilling can happen and subvert this trope. This is the polar opposite of Forgot About His Powers, in other words, an Inverted Trope. Compare and contrast with Amnesiac Resonance, Instant Expert, No Stat Atrophy, Suddenly Always Knew That, and Centipede's Dilemma.
- Dragon Ball: At one point, Goku learns a technique called the Spirit Bomb. He stops using it after the fight with Freeza. Years later (over a decade, at the least), he is reminded to use this technique on Kid Buu by Vegeta, and Goku is still able to use it like a pro.
- Dragon Ball GT: Played with quite oddly. After being turned back into a kid, Goku is unable to use his Instant Transmission technique and Trunks theorizes that since Goku is a kid again, he can't use any technique he learned when he was an adult. However, Goku pulls off the techniques of flying, turning Super Saiyan, shooting out ki blasts, and sensing energy with little difficulty... despite the fact that he never learned them back when he was a kid. The show later implies that like turning Super Saiyan 3, it simply requires energy and stamina his child body simply isn't capable of.
- Dragon Ball Super: After not using it in-universe for almost two decades (he did use it once in Filler, but even then only in the afterlife, where his body doesn't have the same limits), Goku busts out the Kaio-Ken against Hit during their match in the God of Destruction tournament. Though it is hinted that he already tried it just some time before the tournament.
- Fist of the North Star: Close to the end of the series, Kenshirou ends up losing his memory. Despite this, he kills off some thugs with Hokuto Shinken with little effort. Clearly, his skills with the martial art can never be forgotten, even if he has amnesia.
- Noir: Kirika's amnesia has not affected her combat skills, which stop just short of supernatural in their efficacy. Then again, like Chloe, she was trained from childhood, probably for years, and amnesia usually doesn't affect procedural memory anyway, so it could kind of make sense. Like Jason Bourne ("How can I know that and not know who I am?"), she comments on the incongruity:
Kirika: I don't know why... I know how to do things like this. How can I know this? How can I know... when I know nothing else?
- The Dark Knight Returns: The story starts off with Bruce Wayne retired for ten years and an alcoholic. However, once he puts the Batsuit back on, he demonstrates that ten years of retirement and alcohol have not caused him to forget his skills at all.
- Huntress Darknight Daughter: In this storyline, Catwoman pulled a Heel–Face Turn, retired from crime, married Bruce Wayne and had a daughter named Helena Wayne. Everything was good for years...until Catwoman got blackmailed into one last job. She was given the job to break her old partners-in-crime into a building, which she executed flawlessly despite having not practiced it for years. One of the members even comments on that.
- XIII: The story starts with a man with amnesia. Just like Jason Bourne, his combat skills are not at all affected by the memory loss.
- In Neil Gaimans The Eternals, Thena demonstrates that though she's spent the last couple of years as a human, with no memory of her godlike immortal self, she's absolutely terrifying in a fight.
- In Lady and the Tramp II: Scamp's Adventure, Tramp has long since retired from his life of crime. However, he unlocks one locked door with awe-inspiring ease, showing that his criminal skills have not degraded in all those years.
- The Bourne Series: Jason Bourne is introduced with having amnesia. However, his memory loss does not affect his combat skills in the slightest:
"I can tell you the license plate numbers of all six cars outside. I can tell you that our waitress is left-handed and the guy sitting up at the counter weighs two hundred and fifteen pounds and knows how to handle himself. I know the best place to look for a gun is the cab of the gray truck outside, and at this altitude, I can run flat out for a half mile before my hands start shaking. Now why would I know that? How can I know that and not know who I am?"
- The Long Kiss Goodnight: Samantha Caine has had amnesia for eight years. But it becomes clear that this hasn't stopped her from executing a Neck Snap, a rabbit punch, and knife moves like a professional.
- True Lies: Double Subverted and Played for Laughs. When Gib says Harry can fly a Harrier jump-jet, despite reportedly not having touched one for fifteen years. For extra points, he says this to the actual pilot of the Harrier. Harry has some trouble at first, crushing the roof of a police car with his nose gear ("Sorry!") and sending the onlookers scrambling for cover with his thrusters, then gets the hang of it and heads off for Miami:
Harry: If I break it, they can take it out of my pay.
- In The Addams Family, The Mamushka turns out to be this, as Gordon can dance it almost instinctively.
- In Harry Brown, Michael Caine's Harry Brown character is a elderly, retired SAS soldier. Gangs roam his neighborhood, and he along with everyone else avoids them. Then one night he's threatened by a punk with a knife. At first he's fearful and trying to get away, but when the punk tries to stick the knife in his chest... The scene ends with a dead punk and Brown deciding it's high time he put the skills he's learned to good use.
- The Bourne Series: Jason Bourne is introduced with having amnesia. However, his memory loss does not affect his combat skills in the slightest.
- Guards! Guards!: Sgt. Colon claims shooting a longbow is like "riding something you never forget being able to ride," while having terrible problems even drawing his bow, let alone aiming. In reality archery is most definitely NOT a case of this, it requires constant practice to keep your hand in. (The main reason crossbows became so much more popular.)
- In Death series: Roarke was quite the accomplished pickpocket and thief in general in his youth. He still is, actually, and he'll never forget his skills at stealing as long as he lives.
- The Mysterious Flame of Queen Loana: Yambo, despite losing his memory from a stroke, still knows how to spot valuable texts among old collections — and how to get them at the best prices.
- Buffy the Vampire Slayer: Xander got magically transformed into an army soldier. After the transformation wears off, he still has the skills he "learned" even though he rarely uses them. By the later parts of the series, however, he admits that he's mostly forgotten them.
- Doctor Who: After being erased from all of time and space, then reappearing as an Auton Roman centurion then re-integrated back into history after The Doctor restarts the big bang, Rory still remembers the whole experience, including details of living as a Roman and constantly guarding the Pandorica for roughly 2000 years despite it technically never happening. Justified since New Rory (along with everything else in the rebooted universe) is created from Amy's memories just like Auton Rory was; as far as she's concerned, they're the same person so he got both of their memories dumped in his head. Technically, none of his memories happened to him, but to someone else in a previous universe who happened to be physically identical.
- Person of Interest: The episode "The High Road" shows a POI who is an expert safecracker who can crack a combination safe by ear. He retired a long time ago and had been living as a husband and family man in the suburbs...until his partners-in-crime found him and pulled him in for one last job. Despite not have practiced for years, he managed to pull off this rare lost art of a skill like a professional.
- Our Miss Brooks:
- One episode sees Mrs. Davis fill in as a nurse for a miserly millionaire, in spite of having left the nursing profession many years before.
- Subverted in the episode "The First Aid Course", where Miss Brooks pretends to have forgotten first aid in order to avoid teaching a night course. This backfires when romantic rival and fellow teacher Miss Enright ends up continuing the course - and Mr. Boynton signs up.
- Revolution (NBC): Exemplified, where the world has suffered an electricity blackout for 15-and-change years, but all of the soldiers have more or less retained all of their smooth skills behind the fighter stick of a Huey helicopter ("The Stand"). In "The Longest Day", the Monroe militia has clearly not forgotten how to execute a drone strike like professionals, in spite of not having occasion to practice in 15 years of a worldwide blackout.
- Dark Forces Saga: Jedi Knight 2: Jedi Outcast has a lot of years go by and Kyle Katarn seems to have lost his Force abilities. However, judging from the way he uses his lightsaber and the speed of regaining his Force abilities, he clearly didn't forget how to use them. This is actually a plot point, he had visited the valley of the Jedi and tapped into the lightside nexus of Force energy for a boost before returning to the academy.
- The Elder Scrolls V: Skyrim: As of the Legendary update, the game has this trope. Even if, for example, you reset your Destruction Magic skill back to level 15 from level 100, you can still cast your Master-level magics that you learned from books. Books that, bear in mind, you strictly must have level 100 Destruction to find.
- Fire Emblem Awakening: The main character Robin/Tactician/My Unit is found in a field with no memory of anything really. However that doesn't stop him/her from using a sword, casting spells, being a master Tactician. Turns out that there is a reason for this.
- Heroes of Might and Magic (Might and Magic: Heroes VI): Lampshaded, where after a Hero and his orc friend, Kraal, hijack a boat, they talk about sailing it:
Kraal: Kraal is island Orc. Will be okay. Sailing is like riding a horse.
Sandor: Because once you know how you never forget?
Kraal: No. Because you fall off a lot. Heh heh heh.
- Infinity Blade: The character you play never loses his experience levels, item mastery, or skills once he gains them. Not even if he dies multiple times, not even if he gets amnesia (which he did in the story), and not even if you go back to the very first cycle.
- The Legend of Zelda: Breath of the Wild: Link has spent the last 100 years sleeping in the Shrine of Resurrection and wakes up without his memories, yet he is still able to pick up any weapon and wield it against monsters.
- No More Heroes 2: Desperate Struggle: Played with. Despite being out of the game for three years, Travis Touchdown can still pull his combat skills like a pro, and he only has to improve on his Stamina and Muscle. However, one of his Dark Side abilities is absent and has been replaced with the ability for Travis to transform into an actual tiger.
- One Must Fall: Played with. While the trope is played straight for the most part, if you enter a tournament without enough to pay the entry fee, your Strength, Agility, and Endurance stats will decrease slightly. Before you commit to it, a message explains that you will work as a mechanic to raise the funds, but your training will be neglected during that time.
- StarCraft II: Heart of the Swarm: Kerrigan is given a gun by Raynor. She has clearly not forgotten how to shoot with it, which is impressive, considering that she had spent four years as a melee character and a human/zerg hybrid. The two even lampshade it by exchanging the phrase "like riding a bike".
- XIII: The story starts with a man with amnesia. Just like Jason Bourne, his combat skills are not at all affected by the memory loss.
- Batman Beyond:
Tim: I'm no Boy Wonder anymore, but that old training never goes away, even at my age.
- Bruce Wayne has retired from being Batman, and has spent years being a bitter old recluse. However, he is a quite proficient fighter (though he no longer has the stamina for a prolonged battle), using his cane not just for attacking but for casually blocking thrown knives. We also occasionally see him throw a Batarang with all of his old pinpoint accuracy.
- In the episode "Out of the Past", he goes into a Lazarus Pit, restoring him to a younger physique and enabling him to fight much as he did his prime.
- In Batman Beyond: Return of the Joker, he still knows how to make the antidote for Joker venom — fortunately.
- When he appears in Return of the Joker, Tim Drake has been retired from his position as Robin for 40 years, but he still retains some measure of his old skills, able to hear a cloaked Batman coming "from a mile away."
- My Little Pony: Friendship Is Magic: Throughout the show, they have stated that Cutie Marks represent a pony's special talent and destiny, implying that a pony could never forget the skills associated to that talent. "Magical Mystery Cure" confirms this. First, by showing that when five ponies get their Cutie Marks switch, they try to do what the Cutie Mark represents, but they fail miserably. Finally, by showing that when Twilight gets them to remember what they are good at, they get their Cutie Marks back where they should be, and that their skills remain the same regardless of what Cutie Mark they have.
- SpongeBob SquarePants:
- Inverted Trope in the episode, "Your Shoe's Untied." Spongebob has not needed to re-tie his shoes in so long, he has actually forgotten how to do so.
- In the episode "Pickles", SpongeBob goes through a Heroic B.S.O.D. when he thinks that he got an order wrong. It gets so bad that he starts wearing his pants on his head and speaking in scrambled sentences. Mr. Krabs figures that if he can get SpongeBob to make a Krabby Patty again, then he'll go back to normal; he even compares it to riding a bicycle, then notices a bicycle on a boiling pot in SpongeBob's stove.
- Happens in Archer when Sterling has a Heroic B.S.O.D. that causes him to think he's Bob. He retains his skills in combat and the Russian language, putting both to good use throughout the episode. As with just about everything in the show, this is frequently lampshaded by him.
- A Real Life example is musician Clive Wearing, who suffered a bout of encephalitis which left him amnesiac and entirely unable to form new memories. Yet he can still expertly play the piano and remember many of the songs he's learned. This is because the part of the brain that stores your acquired skills is different from the part of your brain that stores experiences. So even if you've forgotten how you learned a skill, you can still perform it.