Keep Our Promise to America's Military Retirees Act

Keep Our Promise to America's Military Retirees Act - Directs the Secretary of Defense to enter into an agreement with the Office of Personnel Management to provide Federal Employees Health Benefits (FEHB) coverage to the following eligible beneficiaries: (1) a member or former member of the Armed Forces entitled to military retired or retainer pay; (2) an unremarried former spouse who was married to a member for at least 20 years, during which such member performed at least 20 years of retirement-creditable military service; (3) a dependent of a deceased qualifying member or former member; (4) a dependent of a living member or former member; and (5) a family member.

Directs the Secretary to reimburse such eligible persons for pharmacy benefits received from a pharmacy that is not a TRICARE (Department of Defense managed health care plan) network pharmacy in the same manner as the Secretary would reimburse such person for such benefits received from a TRICARE network pharmacy. Requires such persons, in order to receive such reimbursement, to submit a certification from their physician stating that the person does not have access to a TRICARE network pharmacy due to physical or medical constraints.

Amends title XVIII (Medicare) of the Social Security Act to waive the monthly part B premium (Supplementary Medical Insurance Benefits for the Aged and Disabled) with respect to: (1) an individual who is entitled to military retired or retainer pay based upon service that began before December 7, 1956; and (2) the spouse, widow, or widower of such individuals.