One bottle is sufficient for 3 months. If you apply Wonderlash every evening, within 4 weeks you will not only get longer eyelashes, your eyelashes will also become fuller, thicker and darker. Wonderlash should be applied once a day to clean skin. You use Wonderlash every evening for 4 weeks. You can then stop for 3 to 4 weeks. If it is necessary again, you can start using the serum again.