And if so, how?
I saw a download available but it says that I have to buy a new license.
At the shop there is no option to buy 8.5
So?
windows 10 64 bit by the way
They only sell the current version, so an update Artist 9.5 is what’s available to you. But with that license you can run all previous Cubase Artist versions.
You always buy the upgrade to the latest version of Cubase license which works to all previous eLc-protected versions of Cubase.
Do not forget to contact info@steinberg.de to ask for Cubase Artist 8.5 full installer after you purchase and activate the license upgrade.
If you want to use Cubase 8.5 because of 32 bit plugins, keep in mind that you can use them in Cubase 9.5 if you buy jBridge, which runs them better than Cubase 8 or 8.5 did.
And again this is not true in general and for all plugins.
I was interested in an update that was made available in the 8.5 and I thought that should I have the chance to purchase that it might be cheaper.
Oh well 
Maybe Soundradix 32 Lives is better: 32 Lives: 32- To 64-bit Audio Units And VST Plug-Ins Adapter | Sound Radix
Again I personally think that the most stable plan is the Vienna Ensemble Pro.