Did you check if it is same as the "run as user"?
As it does not appear in the new version of the product after installation, I would assume it was a created user, and it was being displayed as an unlicensed users because of the scenario below. (see bolded section below)
Name (Site Membership) / Site Role: If the user is not a server administrator, you can assign a user to zero or more sites, along with a site role for each site. You do not have to choose site membership and site role at this time. If you don’t specify site membership and site role for a new server user, the user will be added as a server user only, with a site role of Unlicensed.
Information was pulled from the following: Add Users to Tableau Server
Hope this helps!