Back End Developer for Subscription Management

We need a Back End developer to help manage subscriptions, licenses, and payment processes for an existing software product. We currently have software www.hiwireprompter.com. It is a subscription based software built in Swift, accepts payments through Paddle, and we manage the licenses on the server. We are looking for someone to develop the back end to manage licenses, in the same manner that Cryptlex and Licensespring does. Ideally we would like a structure to implement with the existing server and payment portal so that we don't interrupt service with existing clients. The work includes improving the current system, ensuring reliable billing and license handling, and supporting ongoing maintenance and updates. This is a part-time role for someone who can work independently and help keep the platform running smoothly over time. We would like to work with someone who will be available after implementing to help us do periodic check ups and help manage the service.