They seem to be beta testing a paid dns service. "On-device firewall is free. The in-the-cloud Rethink DNS content-blocking resolver has both free (public beta

They seem to be beta testing a paid dns service. "On-device firewall is free. The in-the-cloud Rethink DNS content-blocking resolver has both free (public beta) and paid tiers (private beta). Currently, pricing isn't implemented and so the private beta is essentially also free till then."