Canon law states that a person may receive Holy Communion twice in one day as long the second time is within the Mass.
Let’s say that you receive Holy Communion outside of Mass one day. You may receive Holy Communion again that same day if you attend Mass and receive It there.
Let’s say that you receive Communion one day, whether outside of Mass or at Mass. You go to a Communion Service later in the day, or some such opportunity to receive Communion outside of Mass. You may NOT receive there.
But a person cannot receive Holy Communion more than twice in one day unless the person is in danger of death, or unless the person is a Priest, who MUST receive Communion at every Mass that he celebrates.
Anybody who tells you that a layperson may receive Holy Communion three or more times per day(unless in danger of death; please see above paragraph) is incorrect.