Adobe Presenter ribbon may not be visible in Microsoft PowerPoint even if it is installed on the computer.
OR
You get an error as C:\Program Files (x86)\Adobe\Adobe Presenter 11.0/MenuLauncher.dll is not a valid office Addin while trying to enable Adobe Presenter
Restart PowerPoint as an Admin (as shown in solution 1) and check if Presenter ribbon is visible in the PowerPoint or not.
Note:
While following the previous step, you may get the following error:
C:\Program Files (x86)\Adobe\Adobe Presenter 11.0/MenuLauncher.dll” is not a valid office Addin.
Try the solution 2 to resolve this error.

Plug-in load error