Cosmetics Formulation Development

If using Witch Hazel in toner over 60 percent, do I need to add more preservative?

Hello, in the case of members who mix for their own use And it's convenient to keep the ready-mixed product in the refrigerator or when the mixture is finished, think it will be used up in 1 month, no need to add. สารกันเสีย is fine, but in the case of production for sale need to be used สารกันเสีย more in the formula.