NO. Sharing a backup will not work as it is encrypted and tied to the serial number for
the device the backup was created on. I was in the same boat you were in when I but
my device second hand outside of the subscription period. The the "cars" are
installed, they are stored in an encrypted manner on the device. You can always use
ES File manager to do a backup, or connect to a PC to access the "external" file system
like a flash drive, but the items you are interested in are already encrypted.

I ended up buying the subscription as I had the MY909/MS908 Pro, and would need
the online coding /calculation features anyway as I work around European vehicles.
The only way I could see what you are asking for to work is if you could root your
device to change your device's serial number and password to match that of the one
you want the backup from. Autel thought of this and blocked access to the developer
options for Android. For those who tried, I see where they get stuck in some sort of
bootloop.

Is it not possible for the manufacturer to provide the option to download the old version without the need to buy an expensive update?