Tile Mate and Slim Combo Pack
I tend to always lose my keys and/or wallet at home. The Tile combo pack was made for me. It comes with a 4-pack (2 smaller and 2 larger ones). The smaller ones have a built-in hook for your keys.
If you lose your item, the tile app (connected via Bluetooth) can show you the last known location. If you are close enough to be in Bluetooth range, your tile can make noise to alert you to its location. You can also use your tile to locate your phone (for those times its in the couch cushion).