Answer
What you are needing here is a Point of entry system for website.
You can do this with Wordpress - where users can register to access. They sign up using wordpress and it's many plug ins.
They would have to choose a email and password to register and that would give them requirements to log back in.
WIth a password to their email you would be able to tell exactly how many times the came in and out of the website.
Explanation:
