The right to cancel will be lost during the cancellation period if the service is provided in full before the 14 days elapses.
If your subscription starts within the 14-day period
In this instance you will still have the right to cancel, but you must pay for the value of the service that was provided to you up to the point you cancel.
For example, if you subscribe and then change your mind within the 14-day time period, you should be refunded a proportionate sum but could be charged for any admin costs.
If the app has been paid for in full within 14 days
The right to cancel will be lost during the cancellation period if the service is provided in full before the 14 days elapses.