So, I've created a web app in HTML and CSS. I want users to pay for the use of this app, and then be able to log in to it. This tool must have specific features:
Users must be able to create their accounts online,
Users must then be able to log-in on my HTML/CSS app.
It must look good (i.e. not plain text on a plain background).
I remember seeing a YouTube advert for one like this. It featured a man coding his own software and taking him 90 days, and with this new app he gets it done in 3. Any ideas?