They're benefitting from drinking more water. Not from the $199.99 Pryme Vessyl. If the issue is that they cannot remember how many glasses they've had (which is never be an issue if you just make sure to drink 2-3 glasses per meal, and remembering to do that is far easier than looking at some app constantly), then give them a memory system.
If they're technophobes, give them a notepad and a pencil for about $2, and let them draw a little line every time they drink a glass of water, or if they insist on a smartphone solution then let them use this free app to count the glasses of water:
https://itunes.apple.com/us/app/daily-water-free-water-reminder/id466387763?mt=8. Draw 8 lines a day for eight glasses of water, or just use the app if the person really, really feels the need to bring smartphones into slurping water.
The coolest thing is that it's compatible with any glass in the world.
Everyone benefits from education about the fact that the body only feels thirst when you're already dehydrated, and that everyone should be drinking 8+ glasses of water a day. The easiest system is to just drink more with each meal (2-3 glasses each at breakfast, lunch, dinner and supper).
Whichever system they use, it's the water that cures them. They'll indeed stop migraines, kidney stones and unhealthy skin (which is indeed caused by lack of water). Their urine returns to healthy (colorless/light yellow) and they rarely feel thirst. They're done, for $0 to $2. They can donate the $198 they saved to the Red Cross or something.
If you had just stuck to developing something like an Apple Watch app to help people with water/health reminders, it would be a neat idea. But an extremely expensive, complicated, battery-guzzling glass and app that needs to be lugged around every day and complicates a total non-issue is just silly.