Let's see, it looks like about a year in the frig... http://www.soapnuts.com/shelf.html. Otherwise, just 3-6 months. That's actually an interesting tidbit about it. Since I'm swishing with it, I *could* keep it in my bathroom, since I'll be using it long before 3-6 months passes!
Thanks for the request for information - I got to learn with you!