Its a standard practice for third party keyboards on iOS, I doubt you'll find any keyboards worth using that don't request full access. Otherwise Apple cripples the experience a lot.

Thank you for checking the app out! Ah that's too bad :( I don't collect any data and the app only connects to the internet at launch (to check subscription status) and when you use the dictionary feature. You can choose not to allow full access and still use quite a few features!