There’s an updated (April 2022) Power Platform Licensing Guide. The main addition is a new table on page 24 showing how AI Builder credits are consumed by the different capabilities. There’s also confirmation added on page 20 that although Power Virtual Agents chat sessions are unlimited per tenant per month, a limit of 10 sessions per user per 24 hours across all bots in a tenant is enforced.
Find this updated guide here: https://bit.ly/3LFWzda.