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I have a key lanyard which is literally attached to my purse. I also have one of those pull apart keychains in case I need to take it off; I rarely do because then I lose them.
My car keys are on a small lanyard with a clasp, which also attaches to my purse.
And my purse? Haha! It's an Osprey Flapjill Courier Bag. You can usually get the previous year's style for cheap on Amazon. I tend to carry books with me, so you can see why I'd need this. Also, it has a pocket for everything.
Within this bag, I portion everything into a clear plastic zipper pouch such as this. So things are easily separated.
White erase boards are a necessity in my house. I have several. They also make magnetic white erase sheets, which you can put on your frig to remind you of the perishables within your refrigerator.
This year I got Susie Shubert's Bad Ass Planner. She has three rows for each day, and I actually use those rows differently than what she has set up. It's an attempt for me to set goals for each month.
I also use the Staples Arc Notebook for project planning and jotting down ideas. This goes into my hefty "purse."
I use Google Calendar (which sends reminders to my phone and email) for everyday scheduling of things like doctor appointments, hair appointments, etc. Basically, anything I have to go out of the house for is in Google Calendar.
Finally, I use the List: Daily Checklist Plus app, which puts a list on my phone to remind me to do the things I have to do every day.
I hope this isn't too big of a list to go through!
I use List, which does what you describe.