Action Needed: Bentley User Registration Requirement

I don't know if this is the correct forum but as we use MicroStation so it seemed OK. Anyway I have just had an email from Bentley with the above in the subject line.

A couple of questions come to mind:

1. What is a 'user' and how do Bentley know how many users we have?

2. Why do users have to register, and how does it "enhance security both for Bentley and for our users".

3. What happens if users don't register?