A market of human-oriented hardware keys, where the keys are only intended to be sold to actual human beings, with legal or otherwise cash bounties in place for people who can provide evidence of the keys being sold to or otherwise falling into the hands of non-human entities.
As mentioned, a bounty system. Someone who buys a thousand to use would have to be very clever to evade the eyes of all the people interested in profiting off of revealing his actions and getting the chips turned off.
