The printer is registered to whichever account it is tied to.
If you buy it and hand it over to someone else, they create an account and tie it to that account.
Think about it this way, you would be unable to sell an old 3D printer if they were perpetually tied to the original purchase.
Not only would that be daft. It would break laws in many countries. This also includes warranties that are for the product not the purchaser.
For a little extra protection, give them a copy of the invoice.