Python Script to Secure Authenticated Web App

I have a python script for sales forecasting. I want it to be a web application (or something similar) that paying customer/company will have access via link (such as in tableau website when you click on "Buy" button: https://buy.tableau.com/). So my app should hava a common link where customers and potential customer will visit and if they buy, and the securely log in, they will be able to use my script for forecast generation.
I have script with streamlit.