If it takes a lifetime, you're overthinking it. . But using it for more than ten or twenty years is not a big problem.
If you are asking about the battery, even though it is a solar watch, the rechargeable battery inside has a lifespan. However, the specific lifespan depends on the specific usage conditions and there is no absolute standard answer.
After using it for more than ten years, I don't need to replace the battery. While it is relatively expensive to use, I have seen people who only need to replace the battery after 3 to 4 years. .