Autodesk Revit addins are generally loaded from the following locations.
User Addins:
%appdata%\Autodesk\Revit\Addins\
Machine Addins (for all users of the machine):
C:\ProgramData\Autodesk\Revit\Addins\
Addins packaged for the Autodesk Exchange store:
C:\ProgramData\Autodesk\ApplicationPlugins\
Autodesk servers and services:
C:\Program Files\Autodesk\Revit 2016\AddIns\
