I think it depends on how serious a runner you are - if you're aiming for something like a 5k in a certain time, or a half marathon, then it gives you really useful feedback. They are just changing things to be a bit more biased on behalf of subscribers so it might be even more worth it to fork out for it. You should be able to look up the strava app on apple play to see what phones it works on. IPhone 5 is quite old now and it's difficult for app developers to make sure all the snazzy new tech works in old handsets and older versions of ios. She might be able to run an app which uploads data to strava though.