We reserved a Small machine but after a few weeks decided it wasn't powerful enough, so today I cloned that server and re-created it as a Medium machine. The Small machine is now powered off.
As I understand it, we will need to reserve the Medium machine since the new machine is of a different type than the one we previously reserved. And unless I make use of that Small machine in some other way, the money we initially paid to reserve it would go down the drain. Right?
Here's the documentation. I think the key phrase here being "in the reserved size" and region. We launched our Medium machine in the same region, it's just of a different size.
Through the Hub you reserve a server instance of a specific size in a specific region. Amazon bills you a non-refundable one-time fee. The Hub applies the discounted hourly rate immediately to any matching server. You'll see this reflected in the server dashboard.