I was able to apply it to one of my mech's weapons in Comp/Con by unlocking the license, going to my mech loadout, and clicking the label that said "NO MOD INSTALLED" on my weapon. However, I had to remove another system from "Systems" for it to show up - if you have no SP free, it will hide the mod unless you hit the "show systems exceeding SP" toggle (the one with the lightning bolt).
Hope that helps!