Launched in July 2017, this is a very different product to the Martini Bitter of the 1990s. The more complex and grander named Martini Riserva Speciale...
Long answer: This is based on rectified grain spirit (effectively very high proof vodka) and does not degrade rapidly. Wine-based products (e.g vermouth, Lillet, Dubonnet) require refrigeration, and even then may have very limited shelf lives.