CLM provides a graphical user interface (GUI) that simplifies installation and helps enable you to automate license acquisition, as well as perform multiple licensing tasks from a central location. You can also use the Cisco License Manager application programming interface (API) to create your own programs for performing licensing tasks.
http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/ios-software-activation/guide_clm_deployment.html
http://www.cisco.com/c/en/us/products/collateral/cloud-systems-management/license-manager/deploy_guide_c07-667473.html