itch.io

"What I published isn't mine anymore, so I won't destroy it, but I can certainly stop selling it."

Yep, that's how I expect things to be! As an author I can cease selling my books, but anyone who has already bought a copy can keep it forever (print or ebook).

It should be the same with games and any software ideally. At least with GOG I can download and keep a file (not that it should be necessary), whereas with Steam the game can be degraded (e.g. music removed from a game you own - I think Rockstar have done that) etc.