To freeze apple cider, transfer it to an airtight and freezer-safe container. Make sure to not fill the container all the way to the top and leave around 1" of space from the top. Do not use a glass container since apple cider will expand once frozen and can cause the glass container to shatter in the freezer. When ready to use, you can either defrost the apple cider in the fridge or carefully defrost it in the microwave. You can even place it straight into a pot and defrost it on the stove.