i never wear it as I can't stand the smell and can't afford the ones that don't irritate my skin. That said 13 is the age I give my kids for a lot of things and seems a fair age. If you are coming into summer tinted sunscreen and lip protection may do the trick while providing protection. Sort out who pays and discuss the hygiene aspects (don't share lipstick with someone who isn't related or whatever you think is important) first though. Sunscreen is a household expense in NZ.