Gahst: Will GOG give me CD KEY ? if GOG pass away, my game passes away, too ?
No, you don't get a CD key because you don't need one. The version on GOG has no copy protection. If GOG passes away, you can still use your local backup, for as long as you want.
What I do is this: I buy a game on GOG, download it (and all the extras), and burn it on a DVD. After that, I'm totally independent from GOG. I can re-install from my backup DVD and play the game whenever I want to - no CD key required, no authentication required, no internet connection required, no existence of GOG required - and all that is actually legal. This is one of the reasons why I'm buying my games here. :)