The version of Cuespeak that is available through the Apple App Store comes with an option to unlock the full library of content. This is done through an in-app purchase (IAP). You have the option of a monthly auto-renewing subscription or a 1 or 3 year non-renewing licence.
To make an in-app purchase you must have set up your device with an Apple ID. As part of this process you normally add a payment method such as a credit card. This payment method will be charged when making any purchases on your device.
Some people don’t want to, or can’t, add a payment method to their Apple ID. To unlock Cuespeak in these cases we would recommend using Apple Gift Cards to add funds to your Apple ID account. These funds can be used for any in-app purchase.