How is the September 11 Security Fee applied to prepaid air transportation?

In the case of prepaid air transportation, if the passenger fully prepaid air transportation prior to December 19, 2014, and the carrier issued a ticket against the prepaid amount on or after December 19, 2014, the carrier must collect the September 11 Security Fee in effect prior to December 19, 2014, for that ticket because TSA considers the air transportation to have been purchased prior to December 19, 2014.