See pricing in Menu → Memberships.
** Price Lock applies as long as you have an active subscription. If you cancel your subscription, you lose your lock. New subscriptions, upgrades, downgrades, and renewals will occur at current pricing. On occasion, price adjustments may be made outside of our control such as Apple adjusting prices due to changing currency conversion rates or compliance with local laws.*
*** Refunds are issued by Apple in accordance with their policy and at their discretion. We cannot issue refunds.*
Open the app, select the menu button in the top right, and tap on Membership.