IDK, but for about a week, my roommate installed and used my copy of BF2 because my computer kept crashing to desktop, so I couldn't play. He installed it and logged into his account, no problem (his acct was from the demo). When I fixed my comp, I just took the disks back and all was well. He has since purchased BF2 (BB deal -- less than $30) and seems to be fine logging in to his acct.