Edited sentence: For homemade mayonnaise it is best to use the freshest eggs possible.Fresh eggs retain the qualities of a living organism including having, or recently have had, an active immune system.Mayonnaise made only from egg yolk and oil will generally only keep under refrigeration for three to four days.Mayonnnaise made at home to have the rich complexity of extra virgin olive oil, yolks from fresh eggs, fresh garden herbs, and vinegar and/or lemon juice is essentially a liquid pickle and can be kept for much longer, especially with refrigeration