You can manage your subscription anytime by navigating to the 'Menu' section and tapping on 'Manage Subscription.'
You can also manage your subscription directly from the Subscription details screen accessible from Menu, where you will find the 'Manage Subscription' option.
This will redirect you to the Play Store/App Store Manage Subscription interface. Alternatively, you could traverse to Manage Subscription interface via Play Store/App Store Account Settings.