Can I block an app from purchases on my Apple account?

You will have to get your son to cancel the subscription, or you will have to remove him from your Family Sharing group so your payment method is cut off from him, or you will have to get him to redeem a gift card to his account so her starts paying for the subscription.

Please click on this link to learn "How to cancel a subscription from Apple" ➔ https://support.apple.com/HT202039

Note:

• "If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew." An "Expires" date (instead of "Renews") means the current subscription will just run until then. "Resubscribe" is just in case you change your mind about having it end.

• Deleting an app does not cancel a subscription.

• If you don’t cancel trials more than 24 hours before your renewal date, your subscription might renew.

• If you don't have an Apple device, see the options near the very bottom of the support document.

"If the subscription that you want to cancel is not listed", click here ➔ https://support.apple.com/HT212052

If you still can't find a subscription, contact Apple Support using the link at the end of the support article.

If you still have problems:

Click here ➔ https://support.apple.com/choose-country-region/media-services Select your country, then a product.

Or: Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here ➔ https://support.apple.com/HT201232

This article explains the different kinds of gift cards Apple uses and has links on how to redeem them and what can be purchased with each kind. Click on the link --> What type of gift card do I have? - https://support.apple.com/HT204199