1. You are trying to type in a password or phone number field. Note that Apple does not allow third-party keyboards to type in these fields. This way, Apple ensures that your privacy is protected and your data remains secure.
  2. You removed the keyboard app. If you remove the app, you automatically also remove the keyboard along with its settings. The app icons look like this:

Keedogo 512

Keedogo

Keedogo Plus icon

Keedogo Plus

Using the same iTunes account that you used to purchase Keedogo or Keedogo Plus, you can redownload the app for free. For instructions, please see this Apple support document.