Research and market data subscriptions are billed on a monthly cycle in advance and if you manage a subscription for any period (even less than a full day) during the month, you will be obligated to pay as if you were subscribed for the entire month.
Note that exchanges do not prorate subscription fees for mid-month elections nor do they offer refunds for subscriptions cancelled mid month. If you cancel a subscription mid-month, however, you will continue to receive the service for the month in which you are billed for the service.
Additional information on market data fees can be found on our website.