How do I provide a monthly subscription to a user?

[Larz60+]

you should learn how to use Flask

Here's a sample subscription service done with Flask, and there are others (google 'flask subscription service templates')
see: https://medium.com/@reedrehg/a-flask-str...b289c11316

I highly recommend Miguel Grinberg's Flask Mega Tutorial: https://courses.miguelgrinberg.com/