Installing Parallels 9 on an iMac that has never had Parallels 8 installed

I previously purchased a DVD version of Parallels 8 but never actually installed it as I was going to change my computer. I now have an iMac with MacOSX Mavericks installed and Windows 8 (which I purchased at the same time as Parallels 8).
If I buy the Parallels 9 upgrade it is a download and I am not sure if that can be installed without Parallels 8 already present. As a new user i am not absolutely sure of the right way to go about this.