Terms and conditions are spelled out when you purchase the product, they don't allow selling of the licenses for their own protection, and the second purchaser.
Lets say you buy a license, then sell it to user number 2, they you dispute the transaction with paypal for your original purchase, and they void the transaction.
Then user numer 2 would have a copy of the license which he could no longer get updates for since their was nothing paid to DBTech