Since I've been asked the question about lifespan and how to take care of scents so many times through PM, here's a lazy copy paste of several of my responses, with slight variations depending on the exact question... Basically avoid heat, light, and air and you're good for many many years.repetitive details: (Click to show)
1. One of the biggest unnecessary concerns out there is about lifespan of fragrances. The whole 'they expire' etc is totally overblown. Basically if they're kept in a dark area (light kills them) and relatively cool or at least consistent temperature (extreme heat is bad, but even room temperature is fine for months at a time), they'll last years and years and I mean like 10+ years. As for evaporation, I have many of these same decant containers and have had them sealed for several years and never seen a single drop of evaporation from them. I promise you they are sealed and will not lose any volume. There are rare exceptions but things like bulb atomizers or toppers that pop on/off instead of spray. Once you've started using a scent and have oxygen in the container, after it's about 2/3 used, then there's enough air that it might start breaking down the scent a little so I'd say finish it up within 6 months at that point but as long is it's unused and sealed and cool and dark, you can keep these for many years without any ill effects. And also another point about the light, but I believe it's mostly an issue about some of the ingredients being photosensitive but I think it's about sunlight specifically so I don't think even just normal indoor lamps will harm them or anything.
2. Will they survive that long? Of course, absolutely. That being said, there are some caveats... The enemies of perfume are heat and light and air. Meaning a cool dark place like a drawer or cupboard is best. Sunlight will kill them or at least turn them dark and kill the freshness. So either keep them in the box or like I said probably in a closed space. And away from heat. Some people store them in the fridge but I think it's a bit overkill unless you live somewhere hot. And I believe that the most damage actually comes from extreme temperature changes plus quick changes, rather than the simple hot or cold. The damage happens when it's 35-40 degrees and the bottle is in your car armrest or something. I've got about 100-200 bottles and they're just in a cupboard in my room so I'm not too worried. It's probably slightly warmer than is 'good' for them but I also have to live a little. The other thing to consider is oxygen, which oxidizes the perfume and makes it deteriorate. So with only a 50ml size there isn't really much air in the bottle, but once you're down to about 30-50% left, you should probably use them up a little faster.
3. As for the question, well hmmm, to be honest it's one of those big myths in the business. Scents can go bad, but they usually don't, or at least nothing silly like in 1-2 years or whatever. Basically heat and light and oxygen are what kill them. So you want dark bottles, stored away from sunlight like in a cupboard/drawer, and once it's about 50% empty, use it up within say 6 months to a year. If you store them on an open countertop, in the glovebox of your car, etc, then yeah they'll die, but otherwise you can get stuff that's 50+ years old and still smells fine if it's been properly taken care of. The delicate topnotes like citrus and some florals usually get 'flat' after a few years but within 15-20 minutes when you're into the heart and base even 'vintage' scents are just fine. So it's sort of a yes and no answer, but for most people with a good head on their shoulders, it's a no. Just a marketing myth to get you to throw out the 'old' and go buy a 'new' one like it's a pair of $100 socks or something.