To upgrade your current subscription to an annual subscription, follow these steps:
For iOS:
From the Chatbooks app, tap into the My Books tab and click into your Subscription.
From there, tap into the Settings found in the upper right-hand corner.
Tap "Manage Subscription."
Under "Billing Cadence" tap "Billing Frequency"
Tap the "Pay Annually" option
Be sure to tap Save and then Done
For Android:
From the My Books tab in your Chatbooks app, tap into your Subscription.
From there, tap into the Settings found in the upper right-hand corner.
Tap "Manage Subscription."
Under "Billing Cadence" tap "Billing Frequency"
Tap the "Pay Annually" option
Be sure to tap Save and then Done