How to change or cancel subscriptions on your iPhone, iPad

1. Go to Settings > [Your Account] > Subscriptions.
2. Tap the subscription that you want to manage.
3. Choose a different subscription option, or tap Cancel Subscription. If you don’t see Cancel Subscription, the subscription is already canceled and won't renew.

How to Restore Purchases on your iPhone, iPad

The premium contents you've purchased may appear locked to you after you switch to a new phone, reinstall the app, or update the app. It can usually be solved right away by manually restoring your premium membership.

To do that,

1. Go to the App
2. Lock screen will be appeared
3. Tap on the Restore button

You should then be able to use the premium contents again. Re-open the app if the change doesn't become effective right away.

Also you can follow these steps,

1. Go to the App
2. Go to the App’s Settings page
3. Tap on the Restore Purchases button

You should then be able to use the premium contents again. Re-open the app if the change doesn't become effective right away.