Weclock: GOG is first-sale-violating too. ;D
DarrkPhoenix: Going off the boilerplate in their EULA this is true; in practice, though, it still remains to be seen. There are no technical measures to prevent someone from selling the installer to another person then deleting all game files and never downloading any of them again, thus effectively transferring ownership. Now, if GOG starts firing off nastygrams and pursuing legal action against anyone trying to do this
then we can definitively say that they are interfering with the right of first-sale.
DarrkPhoenix: There's no way to remove one's
access to a copy of the game, but removing all copies from one's computers is naturally quite trivial. Now, whether this little arrangement would hold up if challenged by GOG in court is unknown, but we are speaking purely of matters of practice here.
Steam can do this too, otherwise phishing wouldn't work.
Your arguing if it can be done, then acting like legalities would be different with steam and Gog.