That's a huge amount of a very hot spice that you are probably never going to use before it loses its potency. My suggestion would be to find some local friends who like hot and spicy and give it away, at least some of it.

Freeze it. I you have a food saver, vacuum seal the bulk of it. The rest just freezer for easy access. It will keep years frozen.

Lots of things I use mine for. A boat load of spice mixes and Korean sauces you can make. Just google 'recipes using Korean pepper flakes' or similar searches.

I posted a Korean pepper sauce I make somewhere. I use about 70% sweet and smoked peppers and the rest the spicy. Mild enough that a Tbsp in a 1/2 pint bbq sauce is not at all spicy. I prefer that those liking super spicy add their own spicy hot sauce at the table.

I must have 4-5 pounds of various dried and flake peppers I stock.

Chili oil!

I talk about it in the pickled mustard thread, here

Many recipes but here is one...and not necessary to use all hot flake. I use some of the mild dried Mexican chilis. Paprika would also make it more mild, less spicy.

chili oil recipe, HERE

At the end of the recipe some links provided for recipes using it.

Here's another chili oil recipe. And if you look at her recipes she uses it in some of them. http://www.marionskitchen.com/homemade-chilli-oil

Definitely store it in the freezer. It does go stale rather quickly and then does not have the flavor that you will want.

I use Korean chili flakes in the sauce when I make stuffed cabbage rolls. The sauce I make is essentially canned tomatoes plus Korean chili flakes. You can also add it to soups or sprinkle it on Brussels sprouts. I tend not to use the chili flakes that much because I keep a good supply of chocolate Habanero sauce that I make every year, and I prefer that flavor. However, I am having trouble getting plants to grow this year, and I may only have two good plants this year. The first batch of seeds that I started sprouting in March did not survive, but the second batch did a bit better, but they are still starting a bit late. However, once the plants get established, they will live for over a year in my back yard.

yeah, well I throw it in my chili ... and use it for a paprika replacement (which I know it's not)

I have a fresh saver (mini foodsaver) that I can re-seal and vacuum multiple times. I use this for re-sealable things such as blueberries I get on sale, nuts etc.. This would probably work well, or suck or press the air out of a re-sealable zip lock bag.

I've used it in recipes calling for red pepper, Korean or not.

Divide into aliquots, freeze.