I plan on keeping most of my collection until I use all of the juice out of the bottle. Sometimes you will notice a change in the scent but if you like the scent still then there is no reason to get rid of it. Good is still good even if it is different. There is no limit or time you should be holding on to your fragrances for. It is entirely up to you. Some people have had their bottles for decades and still like them just fine. You choose.