While you may cancel your subscription at any time, Sortd works on a recurring subscription and you will have access to paid features until the end of your subscription period.  

The monthly subscription period works relative to the day of the month when your subscription first started.  So if you started your subscription on the 20th of the month and you cancel your subscription on the 15th of the following month, you will have 5 days where you still have access to paid Sortd features before the subscription is cancelled.