Before anything, you need to figure out why they aren't willing to pay you. Is this just a matter of a junior dev not having the ability to actually put a card

Before anything, you need to figure out why they aren't willing to pay you. Is this just a matter of a junior dev not having the ability to actually put a card on file or perhaps they haven't had enough time to actually test out your product and present it to their paying client. I'd write an email something like this: Hi XXXX, Thanks so much for signing up again! It's normally against our policy to have two identical trial accounts so I've extended the free trial on your initial account so that you can continue using our service. At [your company] we work very hard to provide value to our customers and I'd love to know what we could do to turn you into a paying customer when your trial expires. Thanks, [you] This gives them the opportunity to 1. make it seem like you're doing them a favor and 2. to let you know what the limitation on their side is.