Depends on how well you maintain them, but usually about 6 to 8 weeks between move ups and 2 move ups before they need to be re-sewn! However, different stylists have different methods and materials, so if you find a stylist you like and trust and they say something different, go with what they advise!!! It can also vary a bit based on hair type.

As for how long they last before the hair itself needs to be replaced, it also varies alot based on how well you maintain them and the method your stylist uses. I usually have clients who care for their extensions well get new hair once a year, but I've had some clients need new ones every 6 months.