Serously... Even on my PC I don't complicate things. I know that buying games on steam only works on Steam and that isn't a problem because almost every game is available there. I dont' worry about offline gaming because there really isn't any verifiable proof that you have 30 days to play. Even then, 30 days is ample time to rectify your connection woes if that's the case.
as it is, it's easy to get over on Steam. you can have your account on multiple computers, but it can only be signed into one at a time. so you can download single player games from one account onto several computers, but then leave them all in offline mode, and play for a month. then you just have to sign in once, and you get another month
obviously M$ doesn't want to let people do that
call it 'Good Guy Valve' or whatever, but these are the kinds of compromises Valve had to make because piracy is such an issue on the PC