Yes, like all beauty and skincare products, lip essence can expire. The expiration date is usually indicated on the packaging, but if you can't find it, there are other ways to check.

1. Smell: The first thing you can do is smell the product. If it has a rancid or off smell, it's likely expired.

2. Color and Texture: Check the color and texture of the lip essence. If it has changed or if it has separated, it might be expired.

3. Performance: If the product doesn't perform as it used to, it might be expired. For example, if the lip essence used to be hydrating but now it seems to dry out your lips, it might be past its prime.

4. Irritation: If the product causes irritation, redness, or a rash that it didn't cause before, it's likely expired.

Remember, the shelf life of lip essence can be affected by how it's stored. It's best to keep it in a cool, dry place away from sunlight. Also, always make sure to close the cap tightly after use to prevent exposure to air and bacteria, which can speed up the degradation process.

Lastly, it's always a good idea to write down the date you opened a product. Most products have a symbol on the packaging that looks like an opened jar with a number and the letter 'M'. This is the Period After Opening (PAO) symbol, and it tells you how many months the product will last after it has been opened. For example, if the symbol says '12M', that means the product will last 12 months after it's been opened.