And if you backup activation data before deactivating, you have both old and new activations working. This could be solved via a "Phone Home" system as Chrysalis suggested. When the user deactivates a PC, the activation server would mark the UID of the motherboard / hard drive as deactivated. Then the next time the PC using the backed up data accesses the Internet, the activation server would see the status of the UID and disable StartIsBack (similar to what would happen if the trial period expired). As of now, and please correct me if I'm wrong, once a PC is activated, the license lives and dies with it. It would be nice to move licenses, especially when it comes time to replace a PC.