Long-lasting wax melts depend on the interaction between the fragrance, wax, warmer, and environment. Fragrance materials with different evaporation rates can create a scent that unfolds over time rather than disappearing all at once. The wax must also release fragrance effectively at the temperatures produced by a typical warmer.
At home, you can help by turning the warmer off when you are not using it and keeping the lid or packaging closed on unused melts. Very high heat can make fragrance release quickly, which may smell intense at first but can also move through the fragrance faster. More heat is not always better.
Strength and longevity are separate qualities. A scent can be bold at the beginning and fade relatively quickly, while another stays quieter but enjoyable across several sessions. Decide whether you want a dramatic first impression or a gentler background scent before comparing products.
Be cautious about judging longevity from a wax ingredient or an 'extra strong' label alone. Try a small amount in your usual setup and notice how it performs later, not just during the first warm-up. Comparing the same portion size and warming time is more useful than comparing how many calendar days two different packs seem to last.