expert in a skill with the Recall Knowledge action, Assurance in that skill
You know basic facts off the top of your head. Choose a skill you're an expert in that has the Recall Knowledge action and for which you have the Assurance feat. You can use the Recall Knowledge action with that skill as a free action once per round. If you do, you must use Assurance on the skill check.
Special
You can select this feat multiple times, choosing a different skill each time. You can use Automatic Knowledge with any skills you have chosen, but you can still use Automatic Knowledge only once per round.
This feat can be selected more than once.
Source: Pathfinder Player Core, p. 252
Bring Automatic Knowledge into a Pathfinder 2e game with The DM Screen.