Instead of PoW or PoS we use proof of threat. Each of our miners is a small but smart honeypot. Hackers see it as attractive target and attack it. Information about a hacker is collected and submitted to BitFence server.
Also Bitfence provides all miners with the basic protection packages. Awesome to keep everyone secure.
i mean honestly I bet you could afford the subscription once you've got a few mining rewards, so technically could get the fully paid solution 'Free'