There are technically three different license types you can own today.
A perpetual license is one that you own indefinitely. Today, you can’t buy a Perpetual license, you would have had to have purchased it prior to the switch-over to Subscription-only licenses. A Perpetual license gives you access to the product you bought. Forever. You have a serial number for that product, and hopefully the installation files either on a disc, a thumb drive, or you’ve downloaded them to your computer. You will want to hang on to those installation files, as Autodesk never promised to make it easy to own a Perpetual license, just that they wouldn’t take it away.
Perpetual with Maintenance Subscription
This is a perpetual license, but because it’s on Maintenance Subscription, you’ll keep moving forward as new versions and updates are released. This is by far the most common license type today. But again, you can’t buy it today. With this license type, you might have bought AutoCAD 2016, but because you pay the Maintenance Subscription fees each year (or every three – depending on your contract length), you have AutoCAD 2017, and AutoCAD 2018, and so on as long as your Maintenance Subscription is still active. You also get all of the subscription benefits, like the ability to run the current version or 4 releases prior to current. As well as subscription updates, like incremental product versions or Productivity Packs and Point Releases. If you ever stop paying the Maintenance Subscription, you’ll be left with a Perpetual license on the release that was current when the Maintenance Subscription ran out. For instance, if AutoCAD 2018 is released in April 2017 and my Maintenance Subscription contract is set for renewal in July 2017 and I choose not to renew, I’ll have access to AutoCAD 2018 forever – but I can’t get access to four releases back, and I won’t get any more updates. I also won’t be able to renew my Maintenance Subscription in the future. When it’s done, it’s done.
This is the only way you can buy today. You have quite a few options when it comes to the length of Subscription you pay for, but you are buying a Subscription, not a product. The Subscription you own will grant you access to the product, however, if the Subscription ever runs out – so does your access to the product entitlement of that Subscription. You have all the same benefits of a Maintenance Subscription in terms of new releases of the product are available to you as soon as they’re available, as long as your subscription is active, of course.
With a Subscription, you’ll be required to sign-up for an Autodesk Account so that you can manage your Subscription. Autodesk now uses what are called “Named Users” for activation of software. So instead of entering a serial number and product key (what the Perpetual license types do), your company software coordinator will add each user to the account and assign them access to the products they need from there. Once the product is installed, the end user will sign-in, and they’re ready to use the product. Each and every user will have a sign-in to the Autodesk Account.