When a customer wants to transfer a license from one system to another. Using a command-line interface (CLI), the user can connect to the original device to revoke its license and specify the UDI - the Cisco identifier that contains product ID, serial number and version information of the target device. The original device contacts the Cisco license portal and requests rehosting permission. When granted, the user connects to the new unit and instructs it to collect the new license, which it does and automatically installs it. Using Cisco License Manager, the user can simply select the source and destination devices from a GUI wizard and the process is automated.
The following URL may help you to know about Automated Software Activation and License Management:
http://www.cisco.com/en/US/products/ps7138/index.html
The following URL explains about License manager:
http://www.cisco.com/en/US/prod/collateral/netmgtsw/ps5734/ps7138/data_sheet_c78_458802.html