Implementing licensing for Desktop Applications

Hi, I'm developing a desktop application and planning to sell it as a monthly subscription; it will incorporate some aspects of locally run, custom, lightweight ML models with some API integrations (planning on having users input their own keys initially, at least for the beta testing phase) – this may change and may host the API & ML models.

I'm a bit new to this and would like to know how I would make sure that only subscribed users can access it while maintaining security and preventing piracy.

What's an optimall way of doing this while retaining scalability; btw, if anyone has experience in, I'm willing to collaborate. Thanks.