Moving a immobiliser tag from one key to another.
I was changing a broken ignition switch in a Subaru Impreza. Since the car was equipped with an immobiliser I had to move the tag from the old key to the new one.
There is a small plastic lid, marked with a red triangle. Use a small flat headed screwdriver to remove it. The tag "CN" will come out. Move the tag to your new key and the job is done.