I have found that my mother is calmer and less confused when she can play a recorded message I leave for her. The message might be something like, "Hi, Mom, today is Thursday, you've had a good breakfast, and Mary is with you. I'll come by this afternoon." She plays it over and over again. Her diagnosis is mild to moderate Alzheimer's. There is an inexpensive, simplified recorder designed for this purpose. It has only one big button for her to push. It's worn as a pendant, so it hasn't gotten lost. I hope it will work for awhile.
My mother has Dementia and I would love to find the recorder you mentioned. She lives in an Assisted Living facility and has been diagnosed with "stage 2-3" dementia. It is very frustrating for me, in that she doesn't remember getting her medication and will call me to say she hasn't received her medication "for 3 days". I know full well that that is not true, but she just doesn't remember getting or taking it.