To upgrade to Fits Pro, simply press the Upgrade button at the top of the home screen. You can also access the Fits Pro checkout page via the app settings.
On the Fits checkout page, you can pick between an annual and a monthly plan. The annual plan is usually discounted.
The payment is securely handled via Apple on iOS or Google on Android. New users get a 7-days free trial (one per user) and you get only charged at the end of the trial.
