I have not contacted amazon directly, but form everything I've read, there is no charge at all from "terminating" contract.
You get 1 year free, then they charge you for the same instance something like 0.07c/h. So if by the years end you simply stop the instance, it will not work, so you would not be charged anything.
You get 1 year free, then they charge you for the same instance something like 0.07c/h. So if by the years end you simply stop the instance, it will not work, so you would not be charged anything.