That's not quite true. Some of their products (Argo; their virtual backbone service) bills on GB; others on requests. That's still going to apply, and it's also going to apply for larger customers on contract.
Once you reach a certain level of traffic (a lot of TBs/month) going through their reverse proxy they will have someone from sales reach out to you and make you to start paying.
Yeah, that's why this is almost unbelievable. What a day. Thanks for the reverse birthday present