I'm a bit confused about the cost of adding a user to a Portal vs ArcGIS Online. The cost for adding users to ArcGIS Online are clear and posted on the web.
Portal deployments appear to come with 55 creators (5 standard, 50 advanced), but I have no idea how much adding more users costs if you use those up.
I would very much appreciate either an answer to this question or a pointer to a link that answers it. I have looked and not found it.