Will the Pro Upgrade Annual Subscription Auto-Renew?
No, by default the Pro Upgrade Annual Subscription does NOT auto-renew.
With that said, when processing your upgrade payment members can choose to pay securely via PayPal/Credit Card OR choose to pay via a PayPal Subscription; the latter will automatically pay for your subscription fees annually, and update your Pro Upgrade subscription expiration date.
If paying via a PayPal Subscription, you can control (e.g. modify/cancel) that annual subscription payment via your PayPal member account.