A copper roof installed correctly can last decades. As with any material, if the installation isn't done well the material can't do its job and will fail, as this copper roof did in less than five years.
These are the front and back of a poorly installed (standing seam, double locked) copper roof. The picture that is mostly brown is copper that was exposed to the air, rain and sun. The area above the brown is very slightly oxidized as it was under the asphalt roof shingles. The standing seam was simply cut and folded sideways at the transition under the shingles. The second picture has a lot of black and patina green color, which I found so pretty that it now hangs on the wall in our office! The problem is that the green patina is the result of water repeatedly sitting on the copper and then drying. So water had been getting under the copper panels (through the way that the installer cut the seam at the transition) since the first day that rain fell on the roof!
Make sure the installer knows what they are doing. Ask them if they know a few industry groups and then look up the installer and the industry group yourself. Revere Copper https://www.reverecopper.com/ and The Copper Development Association https://www.copper.org/ are two very good resources for the architectural sheet metal industry. We are focused on historical metal applications (nearly 100% copper) and these two groups have been dealing with metal for a very, very long time, Revere Copper was started in 1801. We aren't that old but we benefit from the collective knowledge regarding a material that's also been around for a very, very long time.