NetBackup uses a series of digits given to you by support after you've bought the product. Licenses are applied to the master server, and some are applied to the media server. The license is assigned to you and your company, and isn't tied to the hostid. It will work on any similar system. The licenses are tied to Unix or Windows, though, so you can't use a key for a Unix master server and put it in a Windows master server. (At least I don't think so.) ;)