lets go back to the original definition of meme,

Memory+gene,

IE, a concept that is shared and survives on its own. I can teach you to do something, which you teach someone else and so on.

those concepts can change and are affected by natural selection, is it isn't shared it dies, if it changes (unintentionally, let's say when you teach someone you change it a bit and that version makes it easier to teach)...

it's a term coined be Richard Dawkins in the selfish gene(he is a bit of a twat but that idea is interesting).

unless you are referring to a very specific kind of meme (like using animal templates for online memes) memes cannot really end. language is a meme, culture is a meme.