QB Pro 2015

I'll share details that to answer your questions about upgrading QuickBooks, dobeluvr.

Yes, it's still possible to purchase a not-subscription based QuickBooks Desktop license. Although, stand-alone QuickBooks licenses are only offered up until the 2021 versions. 

There are two options on how you can get it. First, you can go to any retail stores or online retailers (Staples, Best Buy, Amazon) that sell QuickBooks licenses. Second, you can process the upgrade inside QuickBooks. Here's how:

1. Go to the Help menu and select Upgrade QuickBooks.
2. Follow the succeeding prompts to upgrade your software.

Here's a similar post where you can see screenshots and additional details: Learn more about upgrading QuickBooks.

Then, follow the steps in these articles on how to move your file to the new version:

• Install QuickBooks Desktop
• Activate QuickBooks Desktop for Windows
• Restore a Backup of Your Company File 

Additional references are also discussed here: What’s New in QuickBooks Desktop 2021.

Don't hesitate to ask more questions if you need anything else. We're always ready to offer our help again.

@dobeluvr 

You can still find and purchase a one time license for QBD 2021 from a few partners. Contact us in private for details.