Their skin is often dry causing fragrances that are too subtle to evaporate rapidly. Dramatic orientals are often favorites. Fragrances don't last forever. There are certain precautions though that will ensure the quality of the fragrance. Keep the bottle in a dry, dark place.
Heat can also destroy a fragrance so keep it from extreme temperatures.
Fragrances usually last 3 years from the date they were manufactured, not the day you buy it. Buy from department stores and reputable perfumeries to ensure the quality of the fragrance. Like everything else, there are high quality and low quality imitation fragrances depending on the quality of the ingredients. Some last 30 minutes on the skin while others last up to 4 hours like their original versions. Not that I know of but some people swear by it.