Butter can be found in several forms each with their particular strengths and weaknesses.
BUTTER POWDER: Probably the easiest to find of the shelf-stable butters the powder is a moisture free product consisting of butter fat condensed on milk solids generally with added antioxidants. It can be reconstituted by mixing with water to make a spread similar to whipped butter, but it cannot be used for frying or other applications requiring high heat that would burn the milk solids. Most butter powders have something of a milky taste due to the additional milk solids necessary to create the powder, but many do not find this objectionable. Because it is a powder (lots of surface area) with a high fat content it needs good packaging to keep it at its best. Vacuum sealing and/or oxygen absorbers will work well if you are doing your own packaging.
CLARIFIED BUTTER (GHEE): Another form of butter suitable for storage programs is clarified butter or ghee as it is known in India. This is fresh, unsalted butter gently heated to drive off the moisture with the remaining fat poured off of the butter solids. It can be purchased commercially but most choose to make it themselves. As it’s essentially pure butter-fat with no water there is little to spoil so will keep for years in a glass jar protected from oxygen, heat, and light. A good source of fat calories and useful in cooking, but maybe not something you’d want to spread on a biscuit.
CANNED BUTTER: For those whom only the real thing will do it’s now possible to find shelf stable real butter. It seems mostly to be sold in those nations where home refrigeration is not as common as it is here in the U.S. As a rule I do not single out suppliers for any given product but Red Feather brand canned butter from New Zealand is the most common. It is salted though not as heavily as most salted butter in the U.S. The manufacturer claims an eighteen month shelf-stable storage life though they do advise keeping it in a cool, dry place. Like all butter it will liquefy it allowed to warm too much. Each can contains twelve ounces (equivalent to about three sticks of butter) and once opened should be handled like any other butter.