All living organisms are made of chemicals which belong to various classes and have different sizes and functions. In the cells, these chemicals are constantly being made and changed into some other biomolecules. These conversions or chemical reactions taking place in the body are collectively known as metabolism. All plants, animals, fungi and microbes exhibit metabolism. Non-living objects do not exhibit metabolism. So we can say metabolism is a defining feature of all living organisms without exception.
Metabolic reactions can be demonstrated outside the body in a test-tube. A metabolic reaction preformed in a test-tube (in vitro) is neither living nor non-living but surely living reaction.