The sec plus license can be purchased from any authorized Cisco reseller, you can google it as asa5510 sec plus license. If no luck with CCO access to above link please call TAC services and ask them how can you register the license after when you purchase the PAK. Try accessing this link, if you get CCO login place your credentials. You will need part number ASA5510-SEC-PL If you have cisco CCO access this is the link to enter PAK and ASA5510 serial number and other necessary information etc. Also always save the output of 'show version' to keep it in your records prior to entering new key upgrade.
When you enter the key in ASA you will need to reboot. Once purchased they will ship you product authorization key known as PAK, once you get that package with this information then you need to go to Cisco license registration page to enter the PAK key and ASA5510 serial number, you will then get the license key by email immediately for you to enter in the ASA5510 and upgrade it to sec plus. Upgrade available with Cisco ASA 5510 Security Plus license. The Cisco ASA 5510 Adaptive Security Appliance delivers advanced security.
