The IAD AC is very venerable - or was in its original guise:
The airline's second club was at Washington's National Airport and opened with the airport in 1939. Located in a "dry" area, the club was prohibited from selling alcoholic beverages. For a nominal fee, however, the club stored bottles for its members. When the Virginia liquor law changed in 1970, so did this club policy. At one point, the club had more than 9,000 bottles stored. Many bore the names of powerful U.S. politicians.
In 1967 the Admirals Club became a paid membership club. Cry your heart out:
A change in Admirals Club membership eligibility was made in 1967 when American established an open policy of accepting dues-paying members – a policy that remains in effect today. The dues in 1967 were $25 per year, or $250 for a lifetime membership. Almost all Admirals at the time decided to pay the fees and retain their memberships.
$250 for a lifetime membership was a bargain - in 2010 dollars, it would be the equivalent of ~$1,614.14.
(Morgan's inflation calculator)