Most likely the software wasn't transferred to Windows 10 due to compatibility. In some cases, Windows deletes the programs that are not compatible and their registry items (the place where registration is stored).
However, if the software still works after Windows 10 upgrade, but it lacks registration, simply add your codes and register it once more. Make sure that the Firewall allows the software to connect to the Internet, in case it requires online Activation.
If the registration doesn't work, contact the developers: http://www.powerkaraoke.com/src/sup_contact.php