There are really only two rules for keeping fuel fresh. The most important is that the container be completely airtight so it can't "breathe" with any temperature changes. Breathing out is ok (except for flammable vapours ) but breathing in allows moisture in the air to get into the container and the moisture is instantly absorbed by the methanol. The next most important thing is to keep it out of direct sunlight because the UV from sunlight can degrade the nitro content of the fuel over time. A metal can obviously is OK but store clear plastic containers in the shade.