You have subscribed to Infinite through the AppStore and at a later date the subscription isn't being detected by the app.

First make sure the subscription still shows up in the AppStore under "Subscriptions".
Next try the "Restore Purchase" button on the Infinite page of the iOS app.

If this doesn't work please send us an email to support@endlesss.fm with your account username. Please include a screenshot of the subscription from the AppStore app.