Calculating Paid Users Count

We provide a service associated with our connect app. While doing business with a new customer we take their word as to how many users the company has per our sales team. We recently started auditing this with the users search endpoint and do a count of active users that are type accountType=atlassian. We found some large discrepancies between the actual user count and what the customer was reporting. After talking with a customer we believe this discrepancy is from “paid” users and “free” users. Currently the users search endpoint doesn’t provide any additional granularity other than active and accountType or any other user endpoint for that matter(we believe). However we believe we found a hacky workaround by fetching all projects and then fetching all assignable users for those projects and remove duplicates. Is this the best approach or is there a better way to calculate “paid” users?