How many times the license "has been used" is irrelevant. The licensing server knows on how many PCs the license is currently installed and restricts the total concurrent installations as defined in the licensing agreement. If you need to move the license from one PC to another, the best thing to do is to remove the license from the first PC by pressing the "Register" button on the Game tab and then pressing the "Remove License" button. That should ensure you have no problem then installing the license on another PC. FYI, uninstalling the software will remove the license, too, but will NOT contact the licensing server. Thus the licensing server will think, erroneously, that the license is still installed.
If you have trouble, always email support@thetournamentdirector.net.