I think I would try Kubotek first and find out their reasonable price would be. If your friend is the original or last registered owner, have them try to get a new key. I think I’ve seen a few seats of Cadkey 19 with the key for sale over the years on the internet for only a few hundred US dollars. Unless you’re not interested in learning new software, you’re probably going to have to buy a new seat of KeyCreator or something different. If this is just a part time endeavor I would consider some cheaper alternatives that are out there that may be cheaper than the key replacement. Getting something that will be able to read your old Cadkey files will be next to impossible if that is an issue.