Question

There is a joke about a child whose teacher informed his parents that he needed Ritalin. Since the parents were uncomfortable with others knowing that he was taking Ritalin, they arranged with the teacher that each day the child would go prepare a cup of tea for him, and while doing so he would take the pill. And indeed, the situation improved miraculously.
When they asked the child what he was doing, he answered that every day he prepares a cup of tea for the teacher and puts the pill in there…
 
I was wondering whether the teacher is obligated to pay for benefit received for the Ritalin.
And this can be analyzed in several ways:
A. The child really did benefit from the Ritalin, in that it calmed the teacher, so he wants that use. (And this is like someone who hosts guests in his home, where they do not need to pay him.)
B. From the moment he put the pill into the tea, the pill was already lost to him; on the other hand, the teacher had not yet received the pill. (The child cannot drink from the teacher’s cup, and from his perspective it is already lost.)
C. It can further be argued that one does not pay for benefit received for such a thing, because even though if his fellow forced food into him, etc., he is obligated to pay even if he could say, “I would have fasted,” one could say that all this applies to food, which is inherently considered property, whereas a pill is property only because of its therapeutic use. And one could say that regarding a person who does not want to treat himself and is fine with his current behavior, from his standpoint this is not a financial gain. If others benefit, let them pay, but he himself cannot be classified as someone who benefited.
I would be happy to hear your opinion on the matter.