Login to CAST Imaging with a user that has been granted the ADMIN role (for example the default "admin" user if you are using local authentication) and click the settings icon:

The system will detect that no license key exists and will instruct you to enter one. Please contact CAST Support to request a license key:

When entered, the license key along with its validity details will be displayed in the license key panel:

To update an existing license key, see Admin Center - License management panel.