This thin strip belongs (I think) to the front of the keyboard. I've attached it with three short pieces of double sided adhesive tape.
Thanks for the fast answer Zipcom , I think it is good idea to use double-sided tape, was the last piece to assemble it all, also think whether it is good idea to use glue, but not if remain good, or stick with glue the base, so it could disarm it in the future for updates , I stopped thinking like they did to paste other people , sorry bad english too