Ticket #208756
"Anonymous users are not counted to the license. We are working to update our documentation to include this information."
Hi, I have a basic license (apart from free, the cheapest license) with allready around 6.000 anonymous users.
But to answer your question, you can find this on the frequently asked questions on https://www.mendix.com/pricing/
If this was what you're looking for, please feel free to accept the answer ;-)