IOS subscriptions are part of your AppleID and are separate from the apps that you use. This can occasionally lead to issues where your subscription status has not synced from your AppleID account to your iPhone app.
To solve this issue just open the iPhone app, tap MORE, tap SUBSCRIPTIONS, and tap RESTORE PURCHASES.
Your subscription is tied to a specific account, meaning that there can be issues with renewing your subscription if you have created multiple accounts within the app. When you tap RESTORE PURCHASES and are not logged into the account that your subscription is tied to the app will prompt you to log in with the correct email address.
If you are having difficulties with your subscription related to multiple accounts please email email@example.com with any email addresses related to your accounts.