This article tells how you can find your Zend Software licenses on the zend.com web site.
Zend Software Licensing
You should be able to find your licenses at zend.com. On most pages on our site there is a 'My Account' link at the top of the page. Please click the 'My Account' link, and log in if prompted. (Please log in with the email address and password you used to create your Zend Account. If you don't remember your password, please use the 'Forgot your password?' link under the 'login' button, and follow the instructions.)
Once logged in, please click the 'Licenses' tab. Under this tab there is a list of your licenses. For each license, the Product Name, Version, Expiration Dates, and Number of Licenses is displayed. If you need to obtain the key to authorize your software, please use this information to locate the desired license on the list. Then click the 'Get License' Action link on that same line. This will display some additional information about the license, including the key, and for some products the order number. You can copy and paste the key (and order number if needed) into the registration dialogue in your software.