Satis is simply a script that compiles some files that can be hosted anywhere where static file hosting is available.
If you want to add access control, it is not a question of using Satis correctly, but implementing access control for static HTTP resources.
By the way: The only authentication protocol Composer offers is HTTP Authentication (aka ".htpasswd"), so if you want a sophisticated payment and access control, you have to implement something that would send 401 HTTP status codes, wait for a username/password and check if that account paid.