Vulneraries and medicines are healing items characters can use on themselves but can’t be used on an ally. They’ll have limited number of uses per battle but they don’t get consumed and disappear from your inventory at the end of battle. Instead, they’ll be replenished until you start the next mission. To use them on your allies, get within range of the allied unit then press R+A. It’s recommended to save these on crucial life-or-death situations since you can conveniently rely on recovery Drops from enemies or jars, even in Hard Mode.