How to Switch Subscriptions from Monthly to Yearly: iTunes – Runkeeper Help Center

Go into your phone's Settings menu, and select iTunes & App Store.
Select your Apple ID, you may not be signed in, if not make sure you sign in with your Apple ID and password for the iTunes Store.
Then select "View Apple ID" and enter your password if you are prompted to.
Select "Manage" underneath "Subscription."
From there, select "Runkeeper"
Where it says "Renewal Options," you can choose whether you'd like to be charged for a monthly or yearly subscription. Your choice will show up highlighted in blue. You can also turn Auto-Renewal off if you do not want a recurring charge.