Is this the area used by some software to store license information - like Solid Works? Or is it ROM?
Userspace software has no way to access it on a typical OS. That's the point. When HPA is disabled it's a usable area of the disk like any other - when it's enabled (usually by the BIOS before handing over to a bootloader - I don't recall if it's persistent, I think it might be), the drive reports a smaller capacity. Very likely what your 'RAID controller' (bleh, fakeRAID) was doing, actually.
If license control software is using it on the fly on a Windows system, they're employing very dirty low level tricks which make me uncomfortable.
What is it's purpose in life?
Variety of tasks. System restore software often uses it to prevent intentional or accidental deletion, along with things like Computrace/Lojack-For-Laptops (the horrific virus that it is), BIOSes have been known to store backup images there (after partitioning, clobbering a valid partition table at the end of the drive - fuck you Gigabyte, fuck you very much).