This doesn't even make sense. If you are charging per click (or view), you don't charge more because of number of visitors, you make more because Revenue=CPCCTRViews (and Views is getting larger).
How is clicking a facebook like button not actively using facebook? I would think that's kind of the definition of being active (as opposed to passive).
And they don't count non-logged-in users. You have to be logged in and either visit facebook.com, or click a like button.