The length of time stitches can stay depends on the severity of the incision. Minor stitches can only stay up to 7 days while some takes about 2 weeks.
1 Additional Answer
From what I know, most stitches in the facial areas will stay in for around 3-5 days. If you have stitches on other body parts, they stay in around 7-10 days normally. Some stitches dissolve on their own.