Google has now added structured data markup for data still in the BETA image license to both the Google Search Console improvement reports and the Rich Tools test tool. If you use this image license markup, you can debug it in both tool sets.
Here is Google's announcement:
We are pleased to announce support for structured image license data in the search console in addition to the Rich Results Test Tool. For more information about the image license, see https://t.co/aqMap8bEby and the Search Console report at https://t.co/8pVYPCW6Oy pic.twitter.com/rJ8Huh33Kp
– Google Webmasters (@googlewmc), July 30, 2020
If you add this metadata and Google decides to display the results in image search, Google may display a new licensable badge for the image. If Google doesn't add the licensable badge, you may want to debug it using these tools.
This is how the badge looks:
Note: If you don't see the "Image Licenses" option in the "Improvements" section of the search console, Google won't recognize the markup on your website at all. It would look like this:
And / or you can run it through the Rich Results test tool to debug your pages in real time.
Forum discussion on Twitter.