Here is the reality: BitTorrent Inc. does not offer giveaways of full product keys outside of occasional promotional contests. Any key you find online falls into one of three categories:
You need a secure way to generate unique keys and store them in a database. : Use a standard format like XXXXX-XXXXX-XXXXX-XXXXX : Use a cryptographically secure pseudo-random generator. bittorrent pro key
Category #3 is the most dangerous.