Feature License Details
The Feature license SKUs supported by Next Generation ISRs can be found below.

Software Activation Feature Licenses:
These licenses are enforced through Cisco Software Licensing Framework.
The HSEC-K9 license removes the curtailment enforced by the U.S. government export restrictions on the encrypted tunnel count and encrypted throughput. HSEC-K9 is available only on the Cisco 2921, Cisco 2951, Cisco 3925, Cisco 3945, Cisco 3925E, and Cisco 3945E. With the HSEC-K9 license, the ISR G2 router can go over the curtailment limit of 225 tunnels maximum for IP Security (IPsec) and encrypted throughput of 85-Mbps unidirectional traffic in or out of the ISR G2 router, with a bidirectional total of 170 Mbps.

The Cisco 1941, 2901, and 2911 already have maximum encryption capacities within export limits. The HSEC license requires the universalk9 image and the SEC license pre-installed.