The PhraseExpress iOS App is a free download and includes a basic feature set free-of-charge for personal use.
It can be extended by "InApp" purchases made within the App to obtain additional features which are outlined in the Apple Appstore description.
It is very important to understand, that all licensing is exclusively handled by the Apple Appstore. Licenses are tied to the Apple account you are using while making a purchase in the Apple Appstore.
Make sure to use the device with the Apple account, you have used to make the purchase. If you change to another Apple account on your device, the App is not licensed anymore.
If you change your iPhone/iPad, all purchases should be automatically recovered if you are using the same Apple account that you have used for the purchase.
Only Apple has insight of any purchase and licensing. We are the maker but do not sell or license the App directly. Apple does. We don't even know of who purchased our App. This is a design decision made by Apple.
Therefore, if you run into any licensing issue, it is important to understand, that Apple is your main contact. They have all information required to establish and/or recover any App license you have purchased.