After your soy sauce has been opened it should be stored in the refrigerator. Storing your soy sauce in the refrigerator at 40°F or below will help it to last longer, and keep it from spoiling.
You may see varying opinions that opened soy sauce kept in the refrigerator, may last anywhere from three months to three years. A lot of it depends on the brand of soy sauce and how your particular soy sauce is made.
You want to use your soy sauce in one year or less after opening. However, you may find the air soy sauce begins to ferment, separate, or have white Floaties in it. These are signs that your sway sauce has gone bad and should be thrown away.
For best results, it’s a good idea to store your opened soy sauce in the refrigerator at 40°F or below for up to three months.