I'm not in the exact same situation as you but I've been on Enza (Xtandi) for 3 years now, and I'm aware that it's typically only effective for around 2 years and tends to lose its effectiveness after 3 years. So the doc may want to review that, or it's maybe just to set eyes on you and have a 'proper' review.
In any event, being 7 years on from diagnosis and still in remission is great, long may that continue!
Wishing you all the best.
Craig