iOS: It's admittedly a little silly to need an app to remind you to grab your key or wallet before leaving the house, or your lunch bag before leaving work for the day, but we all forget those things from time to time, especially those of us coping with mental illness. Don't Leave It! helps you remember.
iOS only (sadly, for the moment), the app is free and just as useful for those of us who just forget our wallets all the time as it is for those of us struggling with dementia or Alzheimer's. It uses geofencing to determine an area around your home, work or any other location around which it will remind you not to leave without picking something up first. So if you set it to remind you not to leave the bar without picking up the credit card you opened a tab with, or not to leave the house without making sure you have your keys, or not to leave your parents' house without the phone charger you leave upstairs, it will alert you before you're a few metres (the app says 60 steps, but that's pretty amorphous) away from where you set it.
Don't Leave It also tries to streamline the alert process, so you can generate it using any of the default items in its selection list (things like keys, wallets, glasses, tablets and so on) or add your own. The app also lets you add custom alerts and notes, and it works offline. It's free and ad-supported, but you can ditch the ads with a one-time in-app purchase for $1.49.
Don't Leave It! (Free) [iTunes App Store]