Help needed 2015 Forester 3171 dead (anti theft activated)

I had the very thing happen to me once with a 2007.5 Dodge. The anti theft portion of the computer quit speaking to the proper key so the vehicle would not start. A tow to the dealer sorted it all out under warranty.

I am not so sure that key you pictured is not chipped. Why do you say it is not? If you are going by size alone, you can be mislead. My Chevrolet key is chipped and is the size of that Ford key.