Every day, morning and night! Use your INIKA lip serum during your regular skincare routine, after cleansing your face. If you're planning to apply lip balm later on, make sure you apply your lip serum first, on dry and clean lips, allowing it to sink in before applying anything else on your lips.
While we do recommend that you use the Lip Serum twice per day (AM and PM), If you want to apply it frequently throughout the day, by all means do so (it's your Lip Serum, after all!), but applying it several times a day won't necessarily give you results faster.