Do not use this app. Please refer to the reviews in your App Store for the reasons why. Depending on your device it may not work and the support staff are inadequate. It works in the short term but not for the long term. You also cannot make a one off payment, you have to agree to a recurring payment plan which depending on how you pay, may be difficult to break from.
please do your homework by checking the reviews by users on this product, not by recommendations by a third party that doesn't test it in the long term.