Much of the cost breakdown for each different HiveMQ service can be found on our pricing page, available here. Specifically, for a further breakdown as to what qualifies as a session, this is available within the technical FAQ towards the bottom of the page. I’ve included the details covered there in this response, as well :
Each concurrent MQTT client session is counted as a single connection. Therefore, if a client device opens more than one session at a time, each one will be counted as a unique connection. These numbers are reset at the end of the monthly billing period.
Example:
If 37 client devices connect every hour on the hour and disconnect after 10 minutes, the total connection count for the day will remain 37.
If 10 client devices connect with a persistent session (cleanSession flag is set to false) and disconnect again, and another 27 devices connect on the hour for 10 minutes before disconnecting the total for the day will also be 37.
Please reach out to HiveMQ support if you have any further questions!