Typically, an offset printing plate has a lifespan of 50,000 to 100,000 impressions. However, this number can vary depending on several factors, such as:

1. The type of printing press
2. The printing speed
3. The paper quality
4. The ink type
5. The plate material

With proper care and maintenance, offset printing plates can last even longer. This includes storing the plates in a cool, dry place and cleaning them regularly to prevent the buildup of ink and debris.