By defalult, the batteries will self-discharge to 50% after 10 days, IIRC. You can set this yourself to something more appropriate to your flying pattern to avoid unnecessary charge cycles as well, e.g. if you can only fly every other weekend they you might want to set it to 14 days instead. They'll hold that charge level quite well for some time, but as noted above, for longer term storage just push the button to check every month or so and give them a charge once they get down to maybe 25% or so.
It's also generally a good idea to store batteries (of any type) that are on the shelf outside the device for any periods of downtime longer than a few days, and ideally in such a way that they cannot be accidentally shorted. I use some of those LiPo Safe bags for this as they give some additional padding against accidental knocks as well, but practice any non-conductive bag or box will do - or even some tape at a pinch. Some people also store them in a fire resistant container like an ammo box so that if they do cook off (it's rare, but it happens) it can't start a more serious fire.
