Thank you for your kind words!
To access your product keys, download links, and manage activations please go to
https://www.radiantviewer.com/store/mylicenses/
Please sign in with the email address used when purchasing licenses.
Click "Show activated computers". There you will be able to deactivate your old machine.
Click "Deactivate this computer" for the machine you want to deactivate. Then you can activate your new computer.