There has been a great deal of debate over how to close the seminar. It's imperative that you don't allow people to leave without an opportunity to make an appointment. If a meal is not offered, you will have to rely on them being self motivated. Their motivation is dependent on how much of a sense of urgency has been created in the seminar. Without a sense of urgency your proposal to do business is extremely passive. Also, you will have little to no opportunity to talk to people before they leave to evaluate their interest level. Calling the next day will lose a significant percentage of people who would have made an appointment if compelled to do so. All of this leads to my real reason for offering a meal. It gives me a chance to see the attendees for a couple of minutes to discover their level of interest, sense of urgency, need, and ability to invest in their future. You will also be able to assess their trust level. Also, you can help them past their reluctance to meet by assuring them that questions can be answered without cost, but solutions require an investment of time and some resources.
Closing your meeting without asking for a decision is a symptom of close reluctance. It is caused by fear. Fear of opinions, fear of rejection, fear of offending, etc. You must put that to rest. If what you do is of real value to the consuming public there is nothing to be fearful of by asking for a decision for something as non-aggressive as an appointment.