We are sorry you experienced this difficulty — please rest assured that you were not billed if a technical issue prevented your subscription from being processed.
Please double-check your Internet connection and try again, as an interruption in access may have occurred during processing.
For Apple users, please make sure in-app purchases are enabled. From your device's home screen, go to Settings, then General, then Restrictions. Scroll down to the section for "Allowed Content." There you can toggle In-App Purchases from "Off" to "On," to allow subscriptions.
If this issue continues to occur, please contact Apple regarding your App Store account or Google regarding your Google Play Store account.
You can find Apple Support regarding purchases and account management here. Select "See all Products and Services" and then "Billing and Subscriptions."
You can find more Android subscription support here, and information on managing your payment options here.