Have you tried always putting them down in the same place?
The OP must be related to Mrs North.
I have tried all sorts of methods but she just isn’t wired up correctly – she discovered she is dyslexic when she did her PhD and I’m sure that it’s connected.
It isn’t just limited to keys or purse or phone. She can leave luggage on trains, shopping at the checkout. She’s loses her handbag and overfilled-and-extremely-heavy work bag. She regularly can’t find her laptop. She’s even lost her car before.
Thankfully, because she’s an blonde, female lecturer I can blame it on her being a ditzy absent-minded academic….
(I’ll look into these tracker devices – good call OP.)