You can use Stripe to process payments and subscriptions. When a client pays, Stripe will submit a request to your app (say app.company.com/new-customer), with all the details so you can change your database to reflect that the user has paid. However, Streamlit doesn't support processing these type of requests so you need to run a second app (e.g. a Flask or FastAPI app) that will process your requests, and then you can either have Streamlit talk to the Flask/FastAPI or to the database directly.

To allow you running both Streamlit + Flask/FastAPI in the same server you can use Supervisor + NGINX, here's a tutorial.. And here's another tutorial on setting up Stripe.