Two User Types: Paid and Nonpaid

Yes you do it with a signup form. One for free users and one for paid users.
You have a field in the database that’s named user type. In your workflow for the signup forms you add user type = free in the one and user type = paid in the other.

On your login page you can do when page is loaded >when user type is xx navigate to page xyz.

Have a look at this example
Continuing the discussion from Requiring login? (SOLVED):