How many access token can I create?

Hello dear Support,

Having Developer Pro plan, how many access tokens can I generate using /token endpoint (using password realm grant type)? Is each call to /token endpoint calculated as a MUA?
I found the term MUA and the calculations which tells if I have 100 users calling 10times to be logged in then MUA = 1000. How many MUA can I have using this plan? What happens if I exceed the limit? Should I pay extra cost for that?

Regards!