Building a subscription app

Has anyone built a subscription app? I think I have an idea on an app that I can post on a web page, that people would be willing to pay for, has anyone done something like this? Instead of a business client and building a platform for them, I was thinking about building something for myself, and then selling access to the app individually. I would obviously need to add each person in as a user, but can I automate this? Is there a service I could use to collect their credit card information and charge them a monthly fee? Maybe appsheet isn’t the right service, but if you all have an idea of a more appropriate service please let me know. It’s just a draft idea running through my head.