Hi,
This should not be a problem....but if you're sing Backup Exec 9.0 4367 or were using it, the issue can occur again.
To prevent it and make sure you have consistent backups, I advise you to uninstall this version (make sure there aren't any remaining reg keys after reboot), and install version 9.1 4691:
http://support.veritas.com/docs/264658
Your license keys will work just fine ;)
Hope this helps
Sam