No, the reasonable thing to do (and the good business practice) would have been to in some ways limit or revoke their access to the API if they didn't pay. Tha

No, the reasonable thing to do (and the good business practice) would have been to in some ways limit or revoke their access to the API if they didn't pay. That way, if they miss the mail and / or choose not to pay, they lose service but no more. Keeping up the service but demanding money with force would make me incredibly wary to do business with them. It's destroying trust and goodwill, and pretty much guarantees that, were I in that position, I'd be looking for alternatives with whom I could have a more healthy business relationship. Need to make money off what used to be free? Fine, but be polite about it. A business operates on the good will of its customers, who they've just annoyed.