Converted Mrs. MileKing's 36K miles to PriorityClub points 2-3 weeks ago. A pathetic conversion ratio but better than nothing. Had seen expiration dates on her account of 2/21/16, 6/4/16, and I believe a few other dates prior to the recent "6 months from date of last activity" which is completely useless since the Frontier website does not seem to display activity correctly. No idea what date was actually correct and wasn't about to take a chance the miles would expire on some random date. And the requirement of activity every six months is more of a hassle than anything else. So, Frontier moves to the back of the line of airlines we will consider flying and they will now be treated as a carrier of last resort.