I had this issue for couple times, after first session I ask them if they want to schedule an other meeting after 1 or 2 weeks, and they agree, but when the time came they find different reason not to came. (free sessions)
I am wandering if I scare them? because at the end of the session I say I kindly ask you to be aware of what nice thinks will happen in to your life until next session and we will talk about what is better in your life... and probably they feel that somehow they did not do something extraordinary to be able to talk about. How should I wrap up the session that the clients may want to come back?