Hey Robert,
Our dev license system unfortunately doesn’t cover subdomains yet, though we are working on this so that folks with staging sites through Flywheel, WP Engine, and other popular sites can use our licenses with the same dev rules as other types of dev sites elaborated upon here → https://theeventscalendar.com/knowledgebase/using-one-license-for-your-live-and-dev-sites/
However, please note that you do not need a license on your dev site at all. The license key does not affect the actual functionality of the plugin in any way—it simply registers a domain name for support and for auto-updates.
So you should be able to use the plugin without a license key fine on the dev site. We’re working on license support for subdomain dev sites, but for now you can just do manual updates and use the plugins unlicensed without issue.
I hope this helps!
Cheers,
George