First, check that your ListenMe subscription is active in the store account used for the purchase. If you use a ListenMe account, check that you are signed in to the correct one.
Update and reopen ListenMe, then use Restore Purchase in Settings
Read the message shown when a feature is unavailable. A usage-limit message may mean you have used your current allowance, even with Pro access. A processing error may require a different troubleshooting step.