This page says to refrigerate after opening.
"Refrigerate after opening; indefinite shelf life when refrigerated"

http://www.amazon.com/Lemon-Oil-Pure-5-oz/dp/B0006Q5OAY

Perhaps it might not be necessary, although perhaps it might be a good idea? Perhaps it might be okay for a few weeks without refrigeration? Perhaps at room temperature it might not spoil, but might degrade in potency over time?