We have an SAP Product, which is an upgrade license, to 2016.  When I go to add a Base License and search for the older 2013 licenses we have of the same product, the search comes up only with the 2016 versions.  I want to make sure I'm adding the correct Base License, as the license in its current state is incomplete.  Is the base license meant to be an older version that we are upgrading, or is it meant to be the same version?