As others have pointed out, the clotting agent is no secret. Actually, my biggest concern about long term storage for a product like QCG is along the lines of what Glock-A-Roo already pointed out--less concern about the stability of the clotting agent, but whether the packaging can keep moisture out long term, especially when jostled and rubbed around in some FAK.

Just the other day, I opened a can of my favorite electrolyte drink and I knew this particular plastic tub had been sitting on the shelf for about two years. There's a foil seal and a dessicant pack inside the powder, but I was a bit disappointed to find the powder was rather clumpy from absorbing moisture. I don't think the amount of moisture affected the drink at all, but just disappointed that obviously moisture had gotten inside. It may be an anomaly, I don't know, but I'm pretty sure that simply sitting around for a while contributed to this result. If I had used it earlier, I have a feeling that it wouldn't have absorbed as much moisture. Now, perhaps a product designed for hard, military use is much better packaged, in which case maybe moisture seeping in is much less of an issue, but Glock-A-Roo's suggestion about storing the QCG inside another bag and let that take the abuse seems to be a prudent one, especially if you want to keep that QCG around a long time.

And I'll just throw this out since it hasn't come up yet, but if you or someone you regularly go to the range with is on some blood thinner (especially something prescription strength) then a clotting agent like kaolin may not help much. Something that doesn't rely on your body's natural clotting factors, for example, something that uses chitosan, may be more appropriate if you really, really want something with a clotting agent. I haven't checked Hemcon in ages, but they may have something out now like QCG that civilians can purchase. They used to only sell band-aids with chitosan to civilians at one point.