At my workplace, our intranet is currently running on sharepoint 2007 server. So we are planning to migrate this to sharepoint 2013 farm using a third-party tool. I wanted to find out how many active users are there in total on the entire sharepoint farm for Licensing purpose. I made lot of Google search and there is no proper guidance or answers for this. It would be great if someone can direct me in a right direction.
One way is to pull all the members of the User Information Lists across all site collections in your farm. After you've amassed that data, you deduplicate it to give you a set of unique users and AD groups. From there, you can pass it through AD to weed out inactive users. That will give you a ballpark of active users in your farm for licensing purposes.
I would have expected the vendor to bill you based on the amount of data you have versus users for a migration tool.