Printer ink cartridge

Does anyone know how to extend the shelf life of an unopened ink cartridge?

I recently bought new cartridges (color & black) for my printer from a company on Amazon. I was hesitant about buying reconditioned ones, but that's the majority of what Amazon handles anyway. I found a company that got rave reviews for the most part, and bought a package of 4 - 2 each of color & black - in the large ink capacity size - for $16 plus change - and free shipping on all orders from them too. That price is about what I pay for one new regular size black one at Staples or Best Buy. This company says they have a shelf life of 2 years, but I probably won't even use one set in that time, since I really don't print that much. Even if the 2nd set dries up before I get to use it, I still got a great price.

So - any ideas on a way to extend the life of the 2nd set - other than just leaving them unopened in the sealed packaging?

I don't really know, but I would think storing them in a cool place is best.

I have some very expensive HP ink cartridges for the A3 printer, three colors and one black, but I can't get that printer to work. :(

I've had cartridges here for over two years and when I do open the ones I need they're fine. And mine have all been refilled at work by my friend. Been ages since I bought new ones, the cost is $27. for one black at Staples , don't remember what I used to pay for the colored cartridges. If I can keep getting the cartridges refilled I'll be happy, what a saving, and so much handier than having to run into Staples . We have other stores that sell them but I found they didn't last. My refills on the other hand seem to last forever-- and I print a lot of pictures and other stuff .
I keep them in a plain small zip lock bag in one of the drawers in my computer desk.