have you deleted of your USB memory stick the file .GiDautority (where the password was stored)?
Then you can use your licence (provided when you bought GiD) to ask again the password for this memory stick in the webpagehttp://www.gidhome.com/purchase/passwords
the page ask for the licence and the memory stick data (name, and sysinfo)
name and sysinfo are showed by the menu Help->Register GiD... window (selecting the memory stick in the list)
Entering the password in this window will save it in the related .GiDautority file (in the root folder of the memory stick)