Is this legal?

It’s entirely legal, yes. As people have been saying for years, you don’t own the games, you own a license to them.

Is it legal to revoke the purchased license just because I don’t use it in a while?

something like: “we can revoke a lisence at any time for any reason” buried in the EULA

Let’s say they decide to revoke a game I newly purchased for no reasons. Shouldn’t that be illegal even tho the EULA says they can do it? If so, where do we draw the line?