fixative

Hello all. I have a beginner question. Do you use fixative for the scent in your liquid soap? If you do, what fixative do you use? If you don't, how do you make the scent of your liquid soap last longer? I have been using essential oils like Lavender, Tea tree and Rosemary, my three favourites...

Is anyone using a fixative in their anhydrous body butter formulations to prolong the scent of fragrance oils? If so, what are your recommendations. Thank you.