In my experience the 5L kits will last a long time (unopened) but the further out the kit is from it's manufacture date, the shorter the life will be upon opening (which can be especially short in partially used bottles left in my JOBO once they've been heated up to processing temps). So I long ago worked out the one-shot amounts for my JOBO processor and split the Kodak 5L E6 kits into these amounts by measuring in graduates. Any opened kit will probably last 3+ mos this way but beyond that you're well advised to purge the oxygen out of the partially full bottles.