Honey does not expire thanks to a mix of many factors. Because honey is primarily a sugar, it does not contain much water, which makes it difficult for bacteria and microbes to thrive. It also has a pH between 3 and 4.5, which is too acidic for most bacteria.
Unspoiled, edible honey has even been found in Egyptian tombs, sealed away for thousands of years. The thickness of honey also helps it last indefinitely. Because it allows very little air into it, honey stays sterile and avoid spoiling. As long as the honey is sealed properly to avoid moisture, it stays fresh forever.