Originally Posted by docbert

Presuming your onward flight is with a non-*A carrier, you will not be allowed access the *A Lounge. In order to be able to access a *A lounge other than a United Club using your United Club card you need to have a departing flight from that airport on a *A carrier.

You will be able to access the United Club in T7 using either your arriving boarding pass or your departing boarding pass (regardless of carrier, until November next year when that rule changes)