The storage will depend to a great degree on how long it will take you to get through that much flour. Most white flours will keep for about a year if kept in a cool, dark place. If you don't think you will be able to use all the flour by that time, then it may be best to break up the flour into smaller packages and freeze them. If you do that, you may want to freeze all the packages, just in case there are any unhatched eggs of little critters in the flour. The freezing will take care of that problem.