Just get in the habit of checking for your keys before you go through any door. It takes no mental effort once it’s a habit.
If they aren’t in your pocket (or in my case a lanyard) then they are in that room or vehicle, so you should recover them before going out. This method worked for me 100% for decades. It only failed after I got married and my wife started stealing them. But it’s usually not too hard to find her.
Just get in the habit of checking for your keys before you go through any door. It takes no mental effort once it’s a habit. If they aren’t in your pocket (or in my case a lanyard) then they are in that room or vehicle, so you should recover them before going out. This method worked for me 100% for decades. It only failed after I got married and my wife started stealing them. But it’s usually not too hard to find her.