Apply Promo Code to an Active Subscription

[nodoc] Reset to free plan and upgrade to get a clean active subscription

Entering an invalid promo code on the promo page shows an error

On the Billing Overview, click the 'Apply promo code' link. Entering an invalid promo code and submitting shows an error.

How to apply a promo code to an active subscription

On the Billing Overview, there is an 'Apply promo code' link. Enter a valid promo code and submit. The Billing Overview shows the discount on the next payment, and the 'Apply promo code' link is no longer shown.

Attempting to apply a promo code when one is already active shows an error

Navigating directly to the promo page and submitting a code shows an error.