The version of Cardiris that is bundled with Canon scanners does not require an activation (license) key.The software should check to see if your scanner is installed (and working) and then it will contact Iris server to complete a self-activation (no key required).
If the Cardris software continues to ask for an activation (license) key, it maybe that you have an older version of the software and it needs to be updated. Please make sure the version you have is v5.8.13.289 or later.
If you version if earlier than v5.8.13.289, uninstall/delete the older version and download/install the latest version which can be found
here.