Officially when you purchase a license for one of our games, it is for use on one computer. If you purchase the game from us, however (as opposed to some of the various resellers who use a variety of different protection software), the game will allow you to use the same registration code on more than one computer in the same household, and we really would not have a problem with that anyway. Please be careful not to share your registration code outside of your household, however, because if it starts spreading publicly we will have to deactivate the code and it will no longer work in the future!