I think the best application of breast milk should be reserved for babies. If mothers can manage it, nurse for at least a year. Some cultures nurse three to five years.

And, I read in an archeological magazine of a dig in one of those cultures — the remains found in those digs showed a clear protein marker in the DNA if the deceased had nursed three years or more. It further indicated that the bone density and determinable health of the deceased individuals were markedly better than those remains without the protein markers. Apparently, that marker typically is not traceable from less than about three years.

Adults using breast milk for their treatments in most cases should be ashamed of themselves. That milk should be made available for babies whose mothers aren't able to nurse or to produce enough milk for their infants. Turning breast milk into just another high priced cosmetic treatment, IME, is shameful.