We get that question on virtually every aerial project – and the answer is complicated!
Officially, the answer is 400 feet above ground level OR the tallest structure around. That means I could fly up to 1200′ if I was above an 800′ structure! In reality – the aircraft will go as high as the battery will allow. Curiously – it’s not how far up it will go that’s the limiting factor – it’s how fast I can descend before the battery runs out. Modern drones will climb much faster than they can descend under control. If any helicopter descends too quickly, they will enter their own unstable air (or “prop wash”) and lose lift. That will cause them to descend even faster – entering what is likely a fatal trip down. To prevent that, descents are limited and take about twice or three times as long as the ascent. So – with 15 minutes of battery, you can climb for probably 4 minutes before spending 12 descending.
1500′ feet is probably achievable easily – but go much higher and it could easily be a one-way-trip because gravity ALWAYS wins.