Did You Know... ATT charges you from the first day the feature has been added to your account through the day the feature is removed.
Example: You add a feature on your account on 5.1 and remove it on 5.14, you are charged for 13 full days of use based on a 30 day month.
Here is the equation: price of feature: $30.00/30 days * 13 full days of use = $13.00 payment required