About 5 years ago I bought a Tascam audio / MIDI interface, but have not really used it. CUbase LE 5 was included so I loaded it up on an old Laptop running Windows XP to check it out. I eventually got it licenced but didn’t have opportunity to use it much at all.
I now have an iMac running the latest version of OS X and when I saw an email from Steinberg offering an upgrade to Cubase LE 8 for only $10, I jumped at it. I now have more time and my sons are getting to the age where they will be interested in using it now too.
Now my problems begin 
I understand that I had bought an upgrade so I tried to load LE 5 onto the iMac as a first step, but it won’t install. It complains that the OS X version needs to be newer that what it thinks I have (but I have the latest - OS X 10.11.x).
Is there a way to install LE 5 on the current OS X version?
If not, I found the old Windows XP laptop and it still has the licenced LE 5 on it. How do I get the licence from the old Windows XP laptop across to the new OS X iMac? Is there a way to do it without needing to buy a hardware key? (The whole concept of Dongles died a slow and horrible death years ago, so I don’t want to have to go there if I can avoid it).
(Rhetorical question: Why does it have to be so hard?)
Any help will be gratefully received - I’ve already lost a few days on this.