sorry its done

I've gotten probably 10-15 games that were locked after I bought them, but Steam has never taken a game away from me. IE South Park, Dead Rising 3, Valiant Hearts, amongst others. I still have and can play all of my games that I got when they were region free and are now locked. Steam has only ever taken away one game from me and that was a game that was in beta that came out of beta.

If you do get it, activate it IMMEDIATELY. The chance of them taking away your access to the game is very slim. I can't even give an example of it happening and if it has happened, its not widespread. If its sitting in your gift inventory, thats another story. If it sits in your inventory and they lock it, then you're screwed. Technically, they can lock games at any time, but if you have it activated, you're almost certainly safe.