what is the shelf life for Clarkia?

Does anybody know what the shelf life is for Clarkia ?

What's the best way to store it, in the refrigerator?

I'm thinking about buying 6 bottles, 2 for me, 2 for my fiance, and a couple more for my pets and maintainence.

I was just wondering if I should buy all six bottles now or as I go. I would like to have them all at once, but am wondering if they will still be fresh by the end of the 11 weeks.

thanks for any assistance and knowledge.