If you bought it on disc, it should just use a disc check and not even need on-line authentication, so no limits there.
For the on-line activation used for DD versions of the game (except, I think, on Steam, where I've heard there is none) there isn't really a limit - certainly not a lifetime one like ME1.
Technically, there is a limit on ME2 DD copies, which is that you can only activate a copy 5 times every 24 hours. (So if 24 hours have passed since the last time you installed the game, you'd be good to install it on 5 more machines. And 24 hours after that you could again install it on 5 more machines.) Effectively it's an unlimited number of activations.
As BewareTheDrow says, DLC is another thing: although you have unlimited installs of DLC, they are tied to your EA account, so there's really no re-selling them. (Unless, I suppose, you create an EA account to use solely for playing ME2.)
Modifié par Kloreep, 08 septembre 2010 - 12:53 .