Hi,
By default the ASA comes with 2 WebVPN License...
I believe you may have something like, somebody was trying to upgrade from 803 to 804, then he fall into the bug CSCsu41224, then he had to upgrade to 804-23 with formatting the flash, when he formats the flash he has to get the activation key once again...
you need to Contact Cisco to get it...
send an email to licensing@cisco.com with the serial number of ASA-1... they should send you the correct license to recover it...
please rate if this helps!