If you cancel your subscription halfway through the subscription period, you will not receive a refund for the other half. However, your subscription will remain active until the end of the subscription period. For example, if you subscribed to the monthly plan of Elder Scrolls Online premium on Dec 1, cancelling the plan on the 15 will not give you half of your money back; your ESO plan will remain active until Jan 1 and cancel before it is set to renew.
All your active subscriptions will display here.