My wife is now 20 months after her stroke and is slowly recovering but she has become a bit absent minded and whilst it's not full blown dementia, it still affects us both.
She runs out of steam at around 10.00pm and retires to bed a couple of hours earlier than me. She is supposed to take a pill when going to bed and another when she gets up in the morning. I keep a track on this by counting the tablets she has left and yes she often forgets to take them.
So I tried a similar trick to the OPs. We leave a very floral egg cup on her beside cabinet and the sight of it reminds her to take her evening tablet and she places the morning tablet in the egg cup and when she sees the it in the morning, she remembers to take her tablet. She now has a 100% track record of not forgetting.
We used to get her to write things in a Filofax and this was only because I used one for work very effectively for decades. However she wanted to do it via her iPhone and after an initial few clangers, she has now got it perfected and she now knows what she has to do today. She also now runs my itinerary for me which allows to be in charge and that's good for her.
Basically let them look after themselves which lets them retain their dignity and keeps the wheels turning so to speak. When your partner gets like this you really do have to act as a team rather than a carer / patient relationship.