Yes, we allow you to make changes to and cancel your subscription at anytime. However, once your renewal date has passed, it not possible to receive any refund.
An example could be: Your renewal date is on the 8th of March. You decide to cancel on the 10th of March (and your subscription is month-by-month). This means that you will have access to Skybox until the 8th of April.
If you have any specific questions regarding this, please contact support here.