It is important to store the shampoo in the fridge, it will last for 7 days! You can also preserve your shampoo by adding Potassium Sorbate that is a mild preservative. The measurement is 2-3g per 1 litre of shampoo and the potassium sorbate should be added at the end of the process, jus before the pH testing and adjusting (it will change the pH a bit so it's important to do the pH correction after adding it :) With this, your shampoo should last at least 6 months. *** You can also consider freezing your shampoo in ice cubes so you can take out one cube each time you want to shampoo. This also allows you to keep your shampoo 3-6 months however the texture may not be as good after unfreezing your product. Up to you to choose which method is the best for you!