Flowsana's pricing works based on the concept of Billable Users. A Billable User is an Asana user who's a member of a team having workflow-enabled projects. Flowsana charges at $2.99/month USD per Billable User. In short, not all licensed Asana users in your organization will be billed. Only users who are members of a team having Flowsana workflow-enabled projects.
Say you have a Marketing team which has 6 Asana users who are members of that team. If you add Flowsana workflows to any projects in that team, you will have 6 Billable Users.
Asana guest users are not counted; like with Asana itself, you don't pay for guests in Flowsana.
If the same user is a member of multiple teams, you only pay for them once. Continuing the above example, let's say you have a second team, Sales, that has 10 members in it, and you add Flowsana to one or more of its projects. But 4 of those 10 users are also members of the Marketing team. Your resulting Billable Users will be 12, not 16, because you only pay for those 4 users once.
Billable Users are recalculated and kept updated automatically by Flowsana, once per day on weekdays. This means there is no concept of purchasing "seats" or "licenses" in advance.
While invoicing and payment occurs once per month, if your number of Billable Users fluctuated within that month, your invoice for the month will reflect a prorated number of Billable Users as it occurred throughout the month.