There will be situations where a configuration key is required to run third party applications, solutions and add-on or to run CCH applications or specifc CCH licences.
When an application has a link with any CCH module or a specifc funcionality is hidden behind a configuration key, then the key should be added to File > Maintenance > User Defined > Configuration.
Configuration keys are developed and improved over time. New configuration keys are shipped with new releases when necessary.
When linking CCH with other applications please refer to CCH guide on the specifc application (for example OneClick or Twinfield) as those will give more information on configuration keys.
If you any question regarding configuration key you can also contact CCH Support.