If one received money which was given to provide for food and
similar necessities but he/she spent the money on other things, if
the intended purpose was not specifically stated as a condition,
one need not return the money nor be otherwise penalized for the
misuse. It is certainly so if the donor is a parent, since sometimes
a parent expects the child to use the money on “unapproved”
things. Nevertheless, the child should request forgiveness from the
parent(s) for not doing their bidding. (Igros Moshe _”__ 1:88)