Originally Posted by AS Flyer

Just to be clear, so that other FA's in the same position aren't assumed to be bad FA's, the FA's are not supposed to "police" who sits in those seats. If someone moves to one of those seats after boarding is finished or during flight the FA is not supposed to ask them to move. That said, if someone sits in the exit row seats that did not pay, they won't be reflected on the seating chart and will not get the free drink or will not have gotten priority boarding. Probably not a perfect system but the FA's mentioned in this post actually went against the policy.