We take a lot of calls from clients who are upset because they can’t activate their older software. Usually, the problem is the fact that they cannot install or activate their older software on their new computers. For example, I had a user call regarding the fact that he could not active his AutoCAD 2000 on his Windows 10 system Yes, you read that correctly. . . AutoCAD 2000 on Windows 10. Now in this example operating systems have evolved and there is no possible way to get that AutoCAD 2000 installed on a Windows 10 system. He, of course, was not happy and stated, "but the software is mine. . .I paid for it."
So let's clarify one thing first. No one has ever "owned" Autodesk software. According to the license agreement (that we all agree to upon installing the software), the license is only granted to us "on loan".
Here it is in writing from the Autodesk Software License Agreement page:
Now If you want to read all the legal jargon about the permissions to use previous versions of the software feel free to read about it on Autodesk's page, Previous Version Rights Benefits Terms for Autodesk Maintenance Plans, Subscription for single-user and Subscription for multi-user.
To sum it up as best as I could. . .
Just because you may have purchased the right to run a given version of Autodesk software doesn't mean you are entitled to use it for eternity. Usage permission is based on the history of the serial number.
For example . . . You may have originally purchased an AutoCAD 2015 perpetual license on a maintenance subscription. And so long as you keep paying that maintenance subscription you are entitled to the next version (so 2015 upgrades to 2016, which then upgrades to 2017, and then once again 2018). As long as you're on an active maintenance subscription you have the permission to run the latest released version and/or three prior versions. This means that if you currently have an active maintenance subscription on a perpetual license, then you can use 2018, 2017, 2016, and/or the 2015 version without any problems. However, when Autodesk releases the 2019 in the near future, the permission to run 2015 software drops and you are only entitled to use 2016-2019.
Here's another example . . . You purchased this 2015 license and was in good standing on a maintenance subscription. Two years go by and you decide to drop the maintenance subscription. The moment you do that, you no longer have the permission to run the 2015 software anymore because you lost the benefit of legacy version usage. At this point you are only entitled to run the most current version at the time you canceled subscription.
Some folks have decided to purchase perpetual software on maintenance subscription believing that they will be allowed to hold onto this software and never have to purchase Autodesk software again. That's a nice thought, but there are other factors at play here like aging computers and operating systems, upgrades in drivers or lack thereof, industry demands, and better tools within the software. Eventually, you will have to make that move forward. And now, the only move to make is to go on subscription. As with other subscription-based software, if you don't maintain your subscription then you will not have access to Autodesk software.