This happens if you once created a free account on use01.thegood.cloud using the same email address as your later paid environment. These are two separate environments that aren’t automatically linked.
Your paid environment continues exactly as you purchased it. The upgrade email only applies to the free account.
Not using the free account anymore? Then there’s nothing you need to do. You can ignore the upgrade invitation; the free account will expire on its own and be deleted afterward.
Not sure if this applies to your situation? Contact us at jointhecloud@thegoodcloud.net and we’ll check it for you.