How is Presto licensed?
Presto licensing is made available two different ways: The first is called Base Pricing that includes a specific number of concurrent users determined by the BCD tier your system falls under. The second licensing option is Unlimited User Pricing, and that includes as many users as you need for your system. Under the Base Pricing option you may license more concurrent users beyond what is included in the Base Pricing option if you need more, however do not want the unlimited user option.