About billing for GitHub Marketplace→
If you install a paid app in GitHub Marketplace, your subscription shares your account's existing billing date, payment method, and receipt.
Upgrading the billing plan for a GitHub Marketplace app→
You can upgrade your GitHub Marketplace app to a different plan at any time.
Downgrading the billing plan for a GitHub Marketplace app→
If you'd like to use a different billing plan, you can downgrade your GitHub Marketplace app at any time.
Canceling a GitHub Marketplace app→
You can cancel and remove a GitHub Marketplace app from your account at any time.