The cake will last if stored in the fridge for up to 3 days. (theeverygirl.com)
Just store in the fridge until ready to serve and beat on high until fluffy, then pipe onto cupcakes. (ourpaleolife.com)
However, if you need to take a break, then store them in the fridge in sugar water and change it out every 7 days to keep them fresh. (kombuchakamp.com)