Rubbercookie: In fear of getting hit by a random banhammer on steam, I always keep an offline mirror of all my offline-playable games and the steam client, as well as registry files on my computers allowing me to use it.
At any time I can plug in that external hdd, start the offline steam in offline mode, and play the remaining games.
I have quite a few games on that service. Suddenly losing them all would hurt bad.
GOG really contrasts that fear by letting you keep what you buy.
That might sound like gog advertisement, but I honestly love how I, for example, still can download, install and play TOCA even though it's "gone" from the store.
Relaxing really.
At least when you compare to the time I had an unstable online connection causing a small bug in steam. Trying to launch a new game I bought gave the me message "Sorry, but this game is no longer available". It doesn't matter if I bought the game only half an hour ago, according to the steam EULA there's nothing keeping Valve from doing just that.
What turned out to be a bug gave me a genuine scare. Ew.
And that is why you don't use Steam, friend. ;)