Which version of Presenter? Which system? Have you actually checked the Office prefs and enabled the Add-In?
I have Office 365 and there was Adobe Presenter. No more is present. I use Windows 7. Only Add-in in options of PowerPoint 2013
is Acrobat PDF maker Office COM Addin. Have to admit I am not to much skilled in that matter.
Moving this discussion to the Adobe Presenter forum.
Chances are it is because something crashed and, being good Windows users, we tend to just click OK on every dialog that comes up. This will disable the Presenter Add-in. To re-enabel it, follow the steps listed here, Presenter 7 add-in disabled itself in PPT 2010 can't enable it.