Ask HN: Selling the developed software after quitting from the company

Hello Guys, Need advice from the community.

While working for a company A, I have solely developed a product and they have started to use it. Now I have quit from company A, but they need my knowledge and support to maintain the software. Should I re-develop the product as a cloud-based service for recurring payment or just provide support and charge per hour? Whats your suggestions guys?