Basic Chrome extension to check if the theme's ID is set to null or a valid number. Returning null indicates the theme was manually uploaded (zip) or possibly an unlicenced theme version.
In Chrome go to chrome://extensions/ and choose the Load unpacked extension option.
In the content.js file there is an optional variable where you can set your Shopify Partner ID. When a valid ID is set an additional link will display in the console to request admin access.