You've gotten lots of good advice already. The only thing I would add is that if you do get a prescription, decide what will work best for his lifestyle--a topical cream or a pill. If he's always misplacing things, then I wouldn't give him a tube of cream to carry around, especially if it's expensive. He could take a pill twice a day and leave the pills at home in the bathroom. Also, creams are more susceptible to high temps, so if he's outside a lot, or if he left the cream in the car, it might liquify.
If he's like me (and some others I saw posting here), intense sun causes them to break out. Definitely have him start wearing some lip protection with SPF. Personally I like Natural Ice. You can find it a Walmart.
I didn't know about the L-lysine. I'll have to check that out for myself!