Wavelab 7 64 bit Version Not working with Windows 10 64 bit

I’m giving up trying WL7 install on WIN10.
I am going to do a new clean system install from a WIN 10 PRO DVD
to get a clean machine for all my software.
I am then intend to buy the WL7 to WL9PRO upgrade for £147.00.
Question. How will WL9 upgrade check that I am a licensed WL7 user.
I have the WL6 DVD, but all the upgrades to WL7 were purchased as
downloads, not DVDs.
Will I have to install WL7 again, which also asks for the WL6 DVD to be read
to prove that you are a registered user.
By the way, Cubase 7.5 works perfectly on WIN10.