You can register through the App Store where you will be able to manage your subscription billing. Please note the billing for the subscription will be managed by the App Store selected not by The Fitness App.
Download My Fitness by Jillian Michaels App
Android - Google Play App Store
https://play.google.com/store/apps/details?id=com.emdigital.jillianmichaels&hl=en_US
iOS - Apple iTunes App Store
https://itunes.apple.com/us/app/my-fitness-by-jillian-michaels/id1190148494