If I purchase a game, is there any way for the developer or Itch.io to remove the game from my computer? Do I own the game or is it a "temporary license"? what are the standards for maintaining live service games after a studio shuts down?
there is no drm on itch's side. if the developer did not do some drm or login/online requirement, games cannot be removed from your computer or be bricked.
the license stays. it says so in the terms. https://itch.io/docs/legal/terms#4-publisher-content
but the elephant in the room is this: there is no guarantee that the files will stay downloadable. devs can delete their pages at any time. it is unprofessional to do so, but this is itch and most devs here are not professionals. there was a case with a rather successful game last year. i do not recall the name, but i think they released it on another platform that required them to remove it or any such crap.
If you buy a game, I would recommend you back up the installation files it up on a cloud server - whichever one you use because as itoldyousoso said, they can be removed from Itch.io. If you keep the installation (zip) files, you can reinstall it.
But even with the backup, the game might stop working after a few years because of updates to Android / Windows etc. So it's not a forever license. There are some games that are regularly updated though - if you click on More information it shows you when the game was published, and when it was last updated. It will give you some idea whether the developer is still supporting the game.