I know ECs are supposed to expire after 12 months of no activity on your account. My trip last year was at the end of August. In July of this year, I made a reservation for the end of September, fully expecting my ECs ($76 worth) to go poof by September 1. They did for one day then came back and stayed there for my trip. I am wondering if making the reservation inside of the 12 month window made a difference. I never thought to ask the MLIFE desk clerk about it when I was there. I stayed at the MGM Grand on a comp offer, if that makes any difference.