Typically, when installing the software, the setup wizard will prompt you for this key early in the process. Without a valid key, the software usually functions in a restricted trial mode or not at all.
Intuit has a "Discontinuation Policy" (often called the Sunset Policy). This policy states that Intuit stops providing software updates, security patches, and add-on services for older versions of QuickBooks after a certain date. Quickbooks Desktop Pro 2019 License Key
If you are looking for a QuickBooks Desktop Pro 2019 license key Typically, when installing the software, the setup wizard