It sort of comes and goes with me. My short term memory is just non-existant. To the point, if I go out with someone, and even spend 5 minutes in a store I can't find my way back to the car right away a good deal of the time if I can't see it upon exiting.
Unless I can see things upon looking around I forget they are there sort of thing. So, while I know I have stuff in my closet in boxes, aside from a few particular items, it happens to just be "stuff" to me. I can't recall what's there or where I put what and all of that.
Losing things, I put all of the things I need daily right next to my bed and if I go out with them I put them in my pockets and put my wallet on top of them in my pocket in case I think they might fall out. It holds them in there for the most part so things won't fall out. My cell phone had a nasty habit if sliding out of my pocket when I'm sitting in the car or somewhere.
Unfortunately when I DO lose something, I need to tear the house apart. I simply can't recall when I had it last usually. I might remember say, getting drunk and partying with my keys a few weeks ago, or dropping ithem on my foot and hurting myself a few days ago. I won't remember however having left them in the door I just opened a few minutes ago carrying groceries in the house. I'll of course check the whole house, before leaving to check to see if I dropped them outside, and upon being completely and irrationally frustrated not finding them outside, see them in the door going back inside.
I used to keep a few odd additions on my key ring, to make it larger and therefore harder to miss. They tended to snap off on me pulling them out of my pocket, so now I have a mess of broken little chains from keychains having broken off of my key ring in addition to my keys.
My pet peeve though is losing books. I end up taking them just about everywhere and I found I need a pocket that they fit into to prevent losing them. Otherwise I'll put them down and forget I carried it in upon leaving and not grab it as I walk out.