My Encore 5 (on Windows 7, 10 & 11 and different hardware over time) has had problems maintaining the serial number, I suspect in the Windows Registey, since installation(s). I probably have to re-license it every 3rd time I use it. I asked about it years ago, and got no improvements from any suggestions. I keep a copy of the serial number (email message) in the directory with the program.
I hope 6 will not have this problem.