My vendor has not supplied my license for my SSM-20 in our ASA 5520s and i would like to enable the module. Can I enable it in detect/alert mode only and just not have the latest signatures or will it even allow me to do that? The signatures are only a couple months out of date.
Yes it will let you 'send' data to it as well as perform any IPS related functions.
You will not be able to install signature updates tough.