The "Expires" check box does nothing when creating a new key:
MENU > Keys > New Key
Click the "Expires" check box. A calendar is presented that a user can
use to choose an expiration date. However, after the key is crated,
there is no "expiration date" set. The resulting key is exactly the
same as if the check box had not been clicked.
Also, I could not find a function to create a 'revoke' certificate for
a key. Does that function exist in GPA?