Apple Pay within Apps on 5s missing

I currently have an iPhone 5s which has the Touch ID security feature. Why doesn't Apple Pay within Apps work for my iPhone 5s? If it will work on an iPad 2 Air and an iPad Mini 3 that both just got the Touch ID why won't it work in my 5s that already has Touch ID? I realize that the Apple Pay won't work with the NFC feature to use at say Panera to pay for something by holding my phone near the terminal but it SHOULD would within Apps. Why is that feature turned off for my iPhone 5s? I'm disappointed and saddened by this lack of inclusion.