The reason you can’t remember where you put something is that you didn’t give it a home.
Instead of putting it back in the same place each time, you put it where it’s most convenient in the moment. A dumping ground is not a home. This applies to your keys, reading glasses, email, files, etc.
The lack of repetition that comes with putting something in the same place each time makes it harder for your brain to recall where you put it. Repetition supports your memory, mental and physical.
Want to make it easier to find something? Give it a home.