What’s the security license for Cisco 1900, 2900, and 3900

Security license for Cisco 1900, 2900(Cisco 2901 router), and Cisco 3900 router

Security License (Paper) for Cisco 1941:  SL-19-SEC-K9(=)

Security License (Paper) for Cisco 2901-2951: SL-29-SEC-K9(=)

Security License (Paper) for Cisco 3925/3945: SL-39-SEC-K9(=)

Security License (E-Delivery) for Cisco 1941:  L-SL-19-SEC-K9=

Security License (E-Delivery) for Cisco 2901-2951: L-SL-29-SEC-K9=

Security License (E-Delivery) for Cisco 3925/3945: L-SL-39-SEC-K9=

You can use the Cisco Network Access Control (NAC) Network Module, which adds the feature-rich Cisco NAC Appliance Server capabilities, with Cisco 2900 and 3900 Series Integrated Services Routers. The Cisco NAC Appliance (formerly Cisco Clean Access Server) is a rapidly deployable NAC product that allows network administrators to authenticate, authorize, evaluate, and remediate wired, wireless, and remote users and their machines prior to allowing users onto the network.

The integration of Cisco NAC Appliance Server capabilities into a network module for integrated services routers allows network administrators to manage a single device in a branch office for data, voice, and security requirements, reducing network complexity, IT staff training, equipment sparing requirements, and maintenance costs.

It is refered from

www.cisco.com/en/US/prod/collateral/routers/ps10538/data_sheet_c78-556151_ps10537_Products_Data_Sheet.html