Disposable vapes should only be thrown away when they are no longer usable. This usually happens when the battery dies or the coil burns out. You can usually tell when it's time to get a new one because the vapor will start tasting bad. It's also evident when the tip no longer lights up at the time of taking a puff.
If you're not sure whether it's time to throw out your disposable vape, then try cleaning it. If that doesn't work, then it's probably time to get a new one. In fact, a disposable vape pen only lasts for around 400 puffs. Read the full guide for more on how to dispose of vapes responsibly.