If you are looking for a key or have lost one, the following "interesting report" details the standard procedures and community findings:
If you previously used RasterLink Pro 5, Mimaki or your authorized dealer may be able to generate a new RasterLink 6 key based on your old Pro 5 serial number. Activating Your License
: If you uninstalled the software but didn't deactivate it, the PC often retains the key info. Reinstalling and starting activation should automatically show the previously used key on the entry screen, provided the "Delete the serial key information" box wasn't checked.