MyFitnessPal, which is owned by Under Armour, wants to harness its 85 million users with a premium paid version of its popular app.MyFitnessPal, a free fitness app that tracks calories eaten rather than exercise, was bought by Under Armour for $475 million back in February. Now MyFitnessPal is releasing its first paid premium version with extra features, for $10 per month or $50 per year, according to a MyFitnessPal blog post.