As a distinguished figure in the realm of clean beauty and skincare, I can provide you with information on lash serums that are popular among individuals seeking to enhance their eyelashes. However, it is important to note that I do not have access to specific information regarding the personal beauty routine or product preferences of individuals such as Kim Kardashian. Celebrities often have access to a wide range of beauty products and may choose to use different serums based on personal preference and individual needs. It is always recommended to consult with a skincare professional or conduct your own research to find a lash serum that suits your specific requirements.