Enabling VPN-3Des-AES

Question

Hello!
I need to enable VPN-3DES-AES on an ASA5540.  Show version provided this info below. 
Licensed features for this platform:
Maximum Physical Interfaces  : Unlimited
Maximum VLANs                : 200
Inside Hosts                 : Unlimited
Failover                     : Active/Active
VPN-DES                      : Enabled
VPN-3DES-AES                 : Disabled
Security Contexts            : 2
GTP/GPRS                     : Disabled
VPN Peers                    : 5000
WebVPN Peers                 : 2
AnyConnect for Mobile        : Disabled
AnyConnect for Linksys phone : Disabled
Advanced Endpoint Assessment : Disabled
UC Proxy Sessions            : 2
This platform has an ASA 5540 VPN Premium license.
After doing some poking around I came across a link to request a free license but when the email came it warned that the requested license was lower than one currently assigned to the serial number provided.  I do not have any of the old license information since this was set up years ago and was way before my time with the company.  Can anyone point me in the right direction on how to enable the feature as well as maintaining my vpn premium license features. 
Thanks,
Andrew

Answer 1

Below is info from the email with the key.  It keeps referring to PIX OX6.1.  The ASA is running ASA 8.0(4).  Is this going to be a problem or are the pix references just there because this key has been needed to activate the strong encryption since the pix days?  Also is the process going to be the same for an asa?  Will I still need a reboot?  Thanks for all the help!
Platform = asa
Installing Your PIX Firewall Activation Key
Note:  On systems running PIX OS 6.2 and higher, you may enter the new activation key via the activation-key command.  A reboot will be necessary to have the change take effect.  On systems running PIX OS 6.1 and earlier, a software image must be downloaded to the PIX Firewall in monitor mode in order to enter the new activation key.
Step 1.  Back up your PIX Firewall configuration.  Use the tftp-server command with the "write net" command to store your configuration on a TFTP server.  Or, use the "write terminal" command to list your configuration and then cut and paste it into a text editing application on your console.
Step 2.  Follow the directions applicable to your version and PIX Firewall model number for installing  a new software and entering a new activation key.  Refer to the PIX Firewall documentation at the following site:
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/index.htm
Step 3.  If prompted to "install a new image," enter y.
Step 4.  When prompted to "enter new key," enter y.
Step 5.  When prompted, enter each of the four key values (Do not enter spaces in the key value).
Step 6.  Use the "show version" command to view the new features enabled by the key.