1.
If you don't want to continue a subscription you need always to cancel that subscription in time, see the following Apple articles:
If you want to cancel a subscription from Apple
If you want to cancel a subscription from Apple - Apple Support
If the subscription that you want to cancel is not listed
If the subscription that you want to cancel is not listed – Apple Support (UK)
Manage subscriptions on Apple TV
Manage subscriptions on Apple TV – Apple Support (UK)
You can modify or cancel subscriptions available on Apple TV, including Apple Music, Apple TV channels, Apple Arcade or individual apps.
See -> Delete apps on your iPhone, iPad, and iPod touch
Delete apps on your iPhone, iPad, and iPod touch - Apple Support
- If you delete an app, it doesn’t cancel in-app subscriptions that you might have. While deleting an app, you might see a Cancel Subscriptions option. Learn how to cancel your subscriptions.
2.
if you a problem with your payment method on your account & you can't make purchases or update / download apps, including free apps, you need to update your payment method or add a new one.
- If you want to change your card, add first the new card, then remove the old one.
- or if you use your Apple ID balance, set your Apple ID balance as your default payment.
See -> Payment methods you can use with your Apple ID
Payment methods you can use with your Apple ID – Apple Support (UK)
You can also use your Apple ID balance as payment method: Add money to your Apple ID balance
Add money to your Apple ID balance – Apple Support (UK)
What you can buy with your Apple Gift Card or Apple ID balance
What you can buy with your Apple Gift Card or Apple Account balance – Apple Support (UK)