When applied properly, extensions can last up to about 6 weeks. The growth and shedding cycle of your natural lashes will cause the extensions to fall out gradually. Since your natural lashes are constantly shedding (each lash on its own individual cycle) you will constantly be shedding extensions. On average a person will lose about 5-10 lashes per week. They can last indefinitely with regular touch ups which are recommended every 2-3 weeks to maintain fullness.