When we think about the any implementation, first question would be on costing and buying needed licenses is one important contributor to it. For PVA also its not a exception. Important thing here is unlike Dynamics 365 licenses which depends on number users accessing the application, it depends of the number of chatbot conversations /sessions. The data storage capacity, data retention strategy also plays important role here. On other side the end users who are using the chatbot won’t need any licenses. Lets see how to find out these licensing requirements and costs.
First we need to ask the customer SMEs expected sessions per month. We can guide them on how to arrive at this number . There must be existing way the expected chatbot users asking questions, raising their queries either sending email to some mailbox, visit the portal and searching or even calling to support number. This data needs to be analyzed and the project team has to forecast the expected sessions per month. Why do we need this information? You can see the way PVA licensing is provided below. However this can change so always better to refer Microsoft site

The Power Virtual Agent license which comes with the tenant if we already have a tenant, or we need to buy for the first time. This license comes with 2000 sessions per month. In case your expected sessions are 5000 per month, then 2000 sessions are available with Power Virtual Agent license and you still need additional 3000 sessions . For this additional sessions , you can go for Sessions add-on which provides 1000 sessions per license per month. Hence you can buy 3 sessions add on licenses.
Now the immediate question would be what is session? As per Microsoft definition “A session is an interaction between a user and bot. The session begins when a user topic is triggered and ends when one of these conditions is met—either: The user’s questions are answered, or the conversation exceeds 60 minutes or 100 turns.”
- The user ends the chat session.
When the bot doesn’t receive a new message for more than 30 minutes, the session is considered closed. - The session is longer than 60 minutes.
The first message that occurs after 60 minutes starts a new session. - The session has more than 100 turns. A turn is defined as one exchange between a user and the bot.
The one-hundred-and-first turn starts a new session.
On the day of writing this post, this is the definition, however it can change in future, hence better to refer the official site always
We have understood how how to calculate the number of licenses based on expected sessions. After this we need to find out how many user licenses are needed and how much data storage is needed for our PVA implementation
Happy Chatting 🙂