Instance admins should be able to turn off new user registration
Problem to solve
If new users can register without administrative permission, this means any user can impact paid seat counts and go over the purchased amount which will then incur a charge and impact the customer's bill without warning.
Proposal
Add the ability for customers to either switch off new user registration altogether and only allow new users to gain access by being added through admin approval, or allow admins to restrict new user registration up to the purchased seat count, at which point when this is reached, the new user registration will automatically disable itself.
Edited by Luca Kisielius