Each license is tied to a subdomain (PRO), domain (Corporate or Enterprise) or IP (Enterprise) and you can't use it in other domain than the purchased one. All licenses also run on localhost and private networks (classes A, B and C).
As you're using a PRO license, if your testing domain is public and distinct than the purchased domain, you can't use it with the same license. There's an special offer for testing environments.
For further information please read the 4th FAQ on http://www.phpdocx.com/faqs