American Airlines sold lifetime passes in the 1980's and 90's to raise money at a time of record high interest. However, the airline didn't anticipate the likes of Steven Rothstein and Jacques Vroom who often rack up over $100,000 worth of plane tickets per month. The LA Times interviews the two frequent flyers who became the target of American Airlines.
http://articles.latimes.com/2012/may/05/business/la-fi-0506-golden-ticket-20120506