Bob should certainly get a refund, prorated with reasonable costs for the actual services. In case service costs are spread over time and many users (i.e. you s

Bob should certainly get a refund, prorated with reasonable costs for the actual services. In case service costs are spread over time and many users (i.e. you sell subscriptions to a service that costs $TONS_OF_MONEY to set up but almost nothing to maintain) some reasonable part can be charged - e.g. a monthly subscription cost - but charging beyond that, or maintaining subscription indefinitely, certainly would not be reasonable. Bob being an asshole and doing bad things is not relevant here - you can't legally rob assholes. You can refuse to do business with them, but that's it, otherwise the assholes have the same rights as everybody else.