Yes it is possible to freeze your conditioner to prolongate shelf life, the product won't become harmful or anything. However it is not a perfect solution either. Here are some things you need to be aware of: 1.Your conditioner will likely separate once you unfreeze it so the texture will likely be uneven and the ingredients not evenly mixed in your product. 2. Once unfrozen, your conditioner will be separated from the preservative (if any) so some areas will be more prone to bacteria growth and turning bad. 3. Frozen product take more space so your bottle may 'explode'. If you wish to try this preservation method, here are some advices: A. If you are doing the conditioner for the first time, we recommend doing a small batches first to see if the formulation fits exactly what your hair needs. So you can iterate faster on the recipe without waste. Then once you know what works, doing a larger batch to keep longer either by freezing your product or by adding potassium sorbate is a very smart way of managing efficiently your routine. B. Be careful not to freeze and unfreeze your conditioner several times. Freeze small portions that you can take out once at a time for a week of use. So you don't have to re-freeze your batch again. C. Label your container so you keep track of when you froze your product. D. Do not freeze conditioner that contains essential oils, as the oils may solidify and become cloudy. F. Once unfrozen, always give a really good shake to your product before using it so you mitigate the separated texture issue.