In order to move your already registered Print2RDP Server to another computer, please make sure that you have transferable license based on the description of How do I know if I have transferable license?
1. To move the already registered Print2RDP Server to another computer, uninstall the product from Control Panel on the computer to unregister the license.
2. When the uninstallation is complete, install the Print2RDP Server on the new computer, and register with your serial number.