It is helpful to measure the freshness and stability of formulations by the PAO: Period After Opening. Once a fresh bottle is opened, this is the amount of time a product stays at its peak performance. For example, the PAO for the Cleansing Oils is two years; they remain lovely and effective for two years after the first use.

Protect your cosmetics with careful storage, avoiding heat, direct light, and oxygen exposure. It is wise to store in a cool, dark place with the lids firmly on. Keep dust caps on too!

For cosmetics kept in steamy showers or on sunny countertops, it is best to pour smaller amounts into separate containers, and keep the larger containers stored in a cool, dark spot for enduring freshness.

It is fine to keep smaller sized products that you use frequently during the day, such as balms, glosses, or perfumes, in your car, pocket, or purse, though balms, butters, ozone gels, and glosses are prone to liquefying above room temperature.

Most products are hearty and have a long period after opening, though it varies by product. Each brand has a different PAO (Period After Opening).

Here is a general list of cosmetics and their period after opening timelines:

 

Period After Opening	Products
6 months	Eye products (including makeup)
12 months	Body Lotions, Crèmes, Scrubs, Face Mists, Hair Care, Ozonated Balms, Shave Crème, Toothpastes, Lip balms + Makeup
18 months	Cleansing Oils, Skin Serums, Masks, Skin Balms, Sun Care, Powders
3 years	Oral Care Serums, Body Butters
5 years	Perfumes, Poetic Pits, Essential Oil Blends, Elixirs
Decades	Essential Oils