When you take as many drugs as I do all day, you have to have a means of keeping track of what you took and when. So I made up these cardboard pill clocks for each drug. They tell me when I took my last dose, and will also indicate when it's safe for the next one.
Yes, I have a pill-minder app on my phone, but I only use it for travelling. This is actually more convenient for me. Sometimes low-tech is the best.