Dirac Software tools can only be installed on one computer at a time. This being said, we understand that one may need to move computers, change OS or sell the unit second-hand. There are 2 possible scenarios:
1) You still have the PC where the old install is still here. Connect your PC to your DDRC unit, make sure you're online with an Internet connection, and uninstall the software from the typical Windows -> uninstall software process. It will communicate back to the licensing server that this license is freed.
2) If you don't have the PC (e.g. Hard drive damage, lost) or option1 didn't work, you can easily reset your license from Dirac self-serve page. Please login with your username and password. You will be able to control the numbers of PC linked to your account and manually kill a license.
Keep us updated if you have any questions.