Ask him if he's taking his medications right and he'll say yes. Every time. That's not the test.
Hand him the actual bottle and ask what it is and what it's for. That's the test.
What this actually reveals
This isn't about catching him. Most of the time, they genuinely believe they've got it handled. The gap between "I'm fine with my meds" and what actually happens when you hand him the bottle is where the real information lives.
Can he name it? Does he know why he's taking it?
Can he read the label without squinting and guessing? That last one tells you something about his vision, which matters just as much as her memory here.
Sit with him through the actual process
Don't ask about it. Watch it.
If he uses a pill box, sit there while he fills it for the week.
Watching the process catches things a conversation never will, a missed day, a doubled dose, confusion about morning versus night.
One pharmacy, one list
If his prescriptions are scattered across different pharmacies, nobody's actually checking for interactions between them. One pharmacy means one person watching the whole picture. Keep a written list of everything he's on, and bring it to every appointment, every specialist, every ER visit if it comes to that.
This one small thing, one list, one pharmacy, prevents more problems than almost anything else you'll set up.
Medication safety is one piece of a bigger picture. The cognition guide in Clarity & Next Steps, "It's Not Just Memory," walks through this and the other changes worth watching for.