TDD does any one check that the S/No. that is listed on your computer is still in the same position in a years time.
This is why we don't track them, as line engineers will put a life jacket back under a seat if found on the floor, which is great until you get more than one in an area.
This can happen with more than one portable oxy cylinders if removed from a stowage during flight, which stowage does the cabin crew put it back in?
I have said previously the only way in my opinion is visual checks on hangar A" checks and the like, not the most cost effected way l know, but stops having out of date items.