Q: ipad app magazine subsription quit

Ddid you, by chance, change your Apple ID recently? You'll have to log in with the old ID, if yes.

Otherwise, Contact App Store support directly. Start with the Contact Us link at the bottom of this page.

View, change, or cancel your subscriptions:

https://support.apple.com/en-us/HT202039

contact iTunes

You tell me to use the 'contact us' button at the bottom of this page. THERE AIN'T NO SUCH BUTTON.

... I have changed some addresses in the past few months, but the app will not recognize either one.

If your addresses changed, your payment might not have gone thru. Log into your Apple ID/iTunes Store and verify everything.

Manage your Apple ID

You can also contact Apple re billing issues directly:

https://www.apple.com/emea/support/itunes/contact.html

https://reportaproblem.apple.com