Licensing a new copy of Cubase Pro 10.5

I’ve been running Cubase Pro 10, but I need to upgrade to 10.5 so I can export video.
I successfully installed Cubase Pro 10.5, but when I try to open it, I get the message “No valid license found.”
I can’t find an option to purchase a license for 10.5 (from 10.0) on the website.
Is it true that purchasing a new license for 12 will let me activate the version I have installed? A pricey option to go from 10 - 10.5…
Any advice greatly appreciated!

MacBook Pro (Retina, 15-inch, Mid 2015)
macOS Sierra 10.13.6 (can be updated to Mojave)

Cubase 10.5 will not run with a Cubase 10 license. You need a license for 10.5 (or above).

You can’t buy 10.5 directly from Steinberg anymore, but as far as I know, you will get a non-upgradeable license for Cubase 11 when upgrading from a previous version to 12 (your Cubase 10 license will became a non upgradeable 11 and you will get a new Cubase 12 license). Please someone correct me if I’m wrong.

That Cubase 11 license will work with Cubase 10.5 (and anything below that).

Thanks so much!
What is a “non upgradeable license?”

You’ll receive a Cubase 11 license that can’t legally be sold or modified in any way other than moving it to another dongle. It’s meant to allow you to use all previous Cubase versions that used the eLicenser system.

It might also be required for verification when you eventually activate Cubase 12 or later for the first time. Cubase 12 uses a new licensing system that allows you to use your Steinberg products on up to 3 computers simultaneously without an USB dongle.