Hi,

lets say that you have two domains with different content. In this case you need additional web license for this domain. However when you are just using domain alias to acces content of your domain then you don't need additional license.

Please see: http://www.kentico.com/docs/devguide/license_management.htm

It states:
"If you use a domain alias (domain name that points to the same web site), such as mydomainX.com or mydomain.net, you also need license keys for these domain aliases. You need to ask support@kentico.com for generating the additional keys (they are free of charge if you already own a license for the main domain)."

So only thing you need to do is to ask support (support@kentico.com) to send you additional license for your alias.

Best regards,
Vita Janecek