Ways to design feature access control for Web App or Phone Apps

Recently I had some discussion with some colleagues about entitlements in Web Apps like SaaS. It piqued my interest on how to design feature entitlements properly for web or phone application.

I can probably have a class in my backend server that represents a product level. Whenever I load a page, I first need to determine what the page needs to show. For extra level of protection, when I process logic on my backend, I also need to check their authority.

My question would be is there any good resources out there to learn more about ways to implement feature entitlements? (I couldn't find any. I am guessing I am using the wrong keywords)