"I wish I knew how this stuff worked," Jon said. The stone glowed, granting his wish, and then he knew.
After just one spray of the "lust potion" on any female of his choosing, that female would forever lust after the first person she saw after the "potion" was sprayed on her. In her mind, she would find a way to justify it, even if it went against her morals.
Jon had to be careful with this, because if he sprayed it on himself, he would lust after the next person he saw, no matter if it was a man or a woman. In his mind, he would justify it, reason that it was fine to lust after the person, even if he knew he was just thinking that way because of the "potion".