Help getting new komplete kontrol set up

Hello, I bought a open box komplete kontrol on eBay and went to register it under my account with native instruments and it says that it has been registered already. The guy I bought it from sells things from estate auctions and says he has no clue who owned it prior to himself or who could have registered it. I have my receipt from eBay that I purchased it. How do I get the license transferred to me without that information of who owned it prior ??? Thanks I’m advance