I'm not an ISP but I assume your previous IP addresses aren't released immediately so you could end up impacting the ISP's business by using up too many IP addr

I'm not an ISP but I assume your previous IP addresses aren't released immediately so you could end up impacting the ISP's business by using up too many IP addresses. If they notice, you might get banned. You could argue that you're not violating the terms of service but it wouldn't get you very far.