Snarwin

Alt+Backspace works in bash too, and should work in any other command-line program that reads input using readline.

Naturally they only get to charge for already-sold copies if you accept the new terms that include the charges. As for how it’s legal to include those charges in the new terms to begin with, I guess you’d have to ask a contract lawyer. Presumably Unity’s own lawyers are convinced they can get away with it, or they wouldn’t have done it.

Unity licenses are sold as a subscription. When the subscription runs out, you either have to renew it and accept the new terms, or lose the license and stop distributing your game.