After going through the steps to purchase the subscription, it might take a few seconds for the status to get updated. Once it does, you should receive the details on your JioSaavn home screen and/or the Pro page regarding the status (success/failure/pending) of your subscription.
Please note: this is available post 9.26 app versions on Android, and. 9.20.0 app version on iOS. In case the payment failed, you should receive the details about the same on the JioSaavn app.