Authorized classic skp on second computer

I have a 2012 Mac OS Mojave computer with authorized Classic skp.
This computer had recent challenges.
I have no other computer (i am a single user)
but would now like to purchase a second computer just in case.
There is a 2017 preowned at Simply Computing with OS Mojave on it.
I would like to buy but only if I may put a Classic skp on it.
I was told I could put the 2021 version on a second computer
because my maintenance was paid to March 3 2021.
Is the 2021 version I may download considered a Classic version
Or is it a Yearly Subscription ? And would the 2021 version work w/ Mojave?
Help on this issue would be so greatly appreciated.
Looking forward to clear answers. Thank you

You appear to have two 2021 Classic licenses. I made the license system send both of them to you.

Not sure why you had two licenses, but with what you have you can install SketchUp on four computers, and apply each license to two of the computers. It is the permanent license, you don’t need to subscribe for SketchUp to work.

The 2017 Mac should be ok, it’s bound to be able to run macOS 10.14 or later (10.14 is Mojave, so what it has already will work, and I’m sure you can take the machine to Catalina or Big Sur if you wish to).

The download for 2021, which you can get directly from this:

Mac SketchUp 2021 disk image

is the same disk image whether you are a subscription user or a Classic license user. When you get to the welcome screen, click on Add Classic License, and add the serial number and authorization code for one of the licenses that just arrived in your email. You don’t need to use the sign in option, unless you use particular features in the program (Extension Warehouse, 3D Warehouse, Add Location, are the main ones).

Thank you so much Colin for clarification
I was sent an email in Nov re/ 2021
But did not understand the details re/ classic or subscription
And left it at that until now re/ challenges with my 2012 computer

I did just received two emails now, in addition to this one, re/ 2021

I will purchase the 2017 laptop OS Mojave 10.14
and pick up in two weeks after I meet my film work deadlines
and will download 2021 at that time

To confirm the 2021 is a purchased forever download

If there are any details I am missing please let me know

Thank you again
I really appreciate
Kind Regards

Yes, both licenses are permanent ones. Also, one of the two licenses still has support until November 2nd 2021.

Thank you Thank you Colin
My anxiety is thankfully dissolving!!