If you restore a system using a backup or migration feature such as Time Machine, Migration Assistant, a backup tool, or disk cloning, the copied VOCALOID product installation may not be recognized correctly.
In this case, uninstall all installed VOCALOID products, and then reinstall and authorize them.
Uninstallation locations
Windows
Start > Settings > Apps > Apps & features
macOS
Applications > VOCALOID7 > Uninstaller
If uninstallation fails, reinstall the VOCALOID product over the existing installation, and then try authorization again.