Offizieller Kommentar
The owner of the license is under no obligation to sell it; the software does not follow the hardware (the hardware does not unlock the software). If they did NOT provide the key for you, you must purchase a license yourself.
If they DID say a license was included but you are having problems with activation, they did not contact Pioneer DJ technical support to release the license from their account, even if they deactivated the rekordbox installation on their computer.