Is Occlusion culling "free"?

No I am not being greedy, but when I am in unity, I notice that I can turn on OCC and layer things as occludes and occluders. if not, I think unity should turn those off for free.

It doesn’t occlude. The switch is there but the Occlusion settings panel in the “Window” menu is not opening up. (Greyed out)

Sorry, the Manual says Pro only:

http://docs.unity3d.com/Manual/OcclusionCulling.html