TFS 1.X+ why does item change uid everytime it's touched?

[TheGahl]

Could someone explain to my why items unique id changes everytime you use/move that item?

I'm trying to make a script that will remove/change an item after certain time once someone used it.
The item could be any item, even gps..

So.. how can I remember the item, without using the uid?

Thanks in advance

 

[Nekiro]

you cant.

 

[Kaspar]

Use, as in using a vial, thus making it an empty vial upon use?
Move as in, moving 1 gp in a stack of more gps?