Noob question on turning my web app into a Saas.

I took a beginner's web dev class and learned how to build some basic projects. I then wanted to build a Twitter app that deletes your last 100 tweets, and was able to do this. All the user does is log into their Twitter and then click a "delete" button. Extremely simple. Now I am curious about how I set up the process that connects a customer paying to them being able to use the app.

​

I know that no one will pay for an app that only deletes your last 100 tweets, the point is just learning how to do it.

​

Could I set up a landing page, have a checkout with Stripe, and then have it direct to my page where they can use the app? How do I set things up so that only people who have paid can use the app?

​

Just looking for the 30,000 foot overview. Thanks.