This vSphere SDK for Perl script retrieves all licenses for either a vCenter Server or ESXi standalone hosts. It will provide you with the name of the license, license key (if you set --hide_key to false, by default it's set to hide the key), the total number of entities supported under the license, the amount consumed which allows you to generate the remainder along with expiration date, hours and minutes of the license key.
For more details, please visit this blog article: http://blogs.vmware.com/vsphere/?p=6113
Here is screenshot of a sample execution:
