Not sure if you have paid your subscription on your iPhone? Follow these instructions:
Tap on the Settings icon on your iPhone
From the settings screen tap on your name
Tap on Media and Purchases
Tap on View Account
Tap on Purchase History
You will now see your purchase history and the last date you paid for your subscription.
Tap on Total Billed and confirm that the payment is Paid and not Pending.
If you need to request a refund, please follow these instructions here: