Obtain the “activation” key from Cisco.
Connect to the ASA, and issue show activation-key to display information about the currently applied license.
The new activation key needs to be applied from the global configuration mode.
In the console simply type conf t to get into the global configuration mode.
Next use the activation-key [YourActivationKey] command to apply the key.
Confirm that the license was upgraded by issuing the show activation-key command again.
You’ll notice in our example, that we successfully upgraded an Cisco ASA 5505 from a 10 (inside hosts) user license to a 50 (inside hosts) user license.