In Jr. High I would track them down for the first couple of weeks of school. If they still weren't coming I would notify the parent that I will no longer be chasing them down for their meds. It's not that hard to remember, as soon as I finish lunch I go to the clinic or I go to the clinic as soon as 5th period is over. It's the same every day. You can remember what class to go to, you can remember to go to the clinic. I would also notify admin. If, after all of that they still didn't come, it was documented that they refused meds.
Truthfully, after a week or two of me not chasing me down, they miraculously started to remember to come for meds.
Disclaimer: obviously, that would not be for cardiac meds. insulin, etc.