It really depends on a lot of factors, such as a skin of your client, technique of permanent makeup, pigments, aftercare and age.

The older your client is the longer it will stay. If you using a light pigment for fair skin it will stay less, then for people with a tan skin. If you client has dry skin it also will stay longer compare to those who has an oily skin. In average permanent makeup lasts from 1 year till 5 years.