Elder's keycard

The elder's keycard is a quest item

Location
The Courier can obtain the elder's keycard by pickpocketing it from either Elder McNamara or Hardin (depending on how they completed the Still in the Dark quest), in the Brotherhood of Steel bunker located in Hidden Valley. It can also be obtained by killing them.

Related quests
This is one of the three keycards required to start the self-destruct sequence during For the Republic, Part 2, Render Unto Caesar or The House Always Wins V and Wild Card: Side Bets.