It appears you are asking about licenses for the ASAs' Firepower service modules. Those are added either in Firepower Management Center (FMC = new name for the old Sourcefire "Defense Center" product) or, if you manage the modules locally, via ASDM.
ASDM management didn't used to be an option for ASA 5545-X thus the (probably very old) instructions you have don't mention it. It was added as of release 6.0 and your firewalls' service modules may be running version 5.x.
FMC is generally recommended as it is much more full-featured than ASDM-based management of the Firepower modules. It is a separately licensed and installed product however.