Here is a troubleshooting excerpt from the article on Differences between iTunes and website subscriptions.
Troubleshooting Playback/ChartBuilder In-App Subscriptions
Are you encountering issues redeeming your iTunes subscription(s) for ChartBuilder or Playback? A common fix for issues caused by expired billing, late payments, etc. is to Restore In-App Purchases.
Playback: Restore In-App Purchase
Log into Playback on the iOS Device with the Apple ID subscribed via iTunes
Navigate to Settings -> About
Tap Restore Purchases
Log in to your Apple ID
ChartBuilder: Restore In-App Purchase
While looking at the chart view, Tap the More menu in the top left
Tap the Gear icon to open account settings
Tap the "Restore In-App Purchases" action at the bottom of the screen
Still encountering issues with an iTunes in-app purchase? Please reach out to multitracks.com/support and we will help address the issue.