There is a chance that Bob might be on the hook for hate crimes or harassment - but that isn't Alice's call. Alice should prorate the cost of service usage to

There is a chance that Bob might be on the hook for hate crimes or harassment - but that isn't Alice's call. Alice should prorate the cost of service usage to the terms of use[1]. If Alice believes Bob might have violated a law during his usage of her service she is absolutely free to report that violation to relevant authorities. Alice has the right to refuse service to Bob for a wide variety of reasons - but it isn't Alice's place to serve punishment to Bob based on a moral judgement of his usage once he ceases to be a client. 1. If Alice expected users to send 2 cards a day and charges a per day rate appropriate to that usage and Bob floods her with 1000 requests a day for a week then that mistake is wholly on her. If you have a per use cost and you charge per day you need to add some kind of rate limiting.