Why can't I hire a Mercenary?:SI
You can hire up to three Mercenaries from your Friends each day by going to the Mercenary Bar and clicking a friend's avatar. In addition to the three Mercenaries you can create, your Friends can recruit more for you by visiting your Base and clicking your Mercenary Bar. Purchasing Mercenary Kits allows you to create up to 25 extra Mercenaries each day. You may support up to 50 Mercenaries simultaneously.