I'm here to share some information about the security when using QuickBooks Desktop 2015, @mgille2.

QuickBooks Desktop (QBDT) 2015 is no longer supported. This means that you no longer receive the latest security patches, and updates, and receive critical security updates. However, if you'll not be using Payroll Services, Live Support, Online Backup, Online Banking, and other services, you can still use your QBDT 2015. However, you can still use any third-party security app or firewall. 

For detailed information about the add-on services that are no longer supported and critical security updates with your QBDT 2015, check out this article: QuickBooks Desktop service discontinuation policy.

In case you'd like to switch to QuickBooks Online (QBO), check out the QuickBooks Online pricing page. Then, refer to this article on how to move your file to QBO: Move your QuickBooks Desktop file to QuickBooks Online.

Let me know if you have further questions about your QuickBooks Desktop account. I'm always here to answer them for you. Have a great rest of the day!