Press-on nails can last anywhere from a few days to up to two weeks, depending on various factors such as the quality of the nails, the adhesive used, and how well they are applied and maintained. Higher-quality press-on nails with strong adhesive can last longer, while those that are applied carefully and with proper preparation (like cleaning and buffing the natural nails) will also tend to stay on better. Additionally, avoiding activities that put stress on the nails, like excessive exposure to water or heavy manual tasks, can help extend their lifespan.