The WPSSO Core Premium plugin is licensed based on the WordPress Site Address URL (see the WordPress General settings page). Typically, development, staging, and production sites would require 3 licenses, as each uses a different WordPress Site Address URL and each needing Premium features and Premium support. In the spirit of helping our fellow developers, we are offering a free development license for every license purchased.
If you purchase a license for your-domain.com (or www.your-domain.com), you can also register dev.your-domain.com using the same Authentication ID. This allows developers to purchase a license, develop a customer’s website, and then change the WordPress Site Address URL value upon delivery, without having to purchase an additional license for the production website.
The developer special also applies to multisite licensing – if you have 2 licenses for your-domain.com/siteone/ and your-domain.com/sitetwo/, you could also register dev.your-domain.com/siteone/ and dev.your-domain.com/sitetwo/ using the same Authentication ID. The installation order is not important – you can register a development site first, and the production site afterwards.
In summary, your-domain.com, www.your-domain.com, and dev.your-domain.com are all considered equal for licensing purposes (they share the same license). All other WordPress Site Address values, like test.your-domain.com, staging.your-domain.com, etc., are considered valid sites and automatically registered if an Authentication ID is entered in the SSO > Premium Licenses settings page.
Note that the .local, .test, .example, .invalid, and .localhost top-level domains are internationally recognized as private use domains – ie. a domain name cannot be registered under these top-level domains. Developers may use these top-level domains for private test / development sites, but since these sites cannot be reached from the internet, they cannot be licensed.