Syncfusion keys are often locked to the major version you purchased (e.g., 2024 Volume 1). If you install Syncfusion NuGet version 26.1.38, but your key was generated for version 25.x, it will fail.
If you don't have a license yet, you can still get a temporary unlock key. syncfusion unlock key link
License keys are version-specific and platform-specific. They are required to remove the "Syncfusion License" watermark from your running application. Licensing FAQ – Get the license key - Help.Syncfusion.com Syncfusion keys are often locked to the major
tab, and select the version and platform (e.g., ASP.NET Core, Flutter, React) to generate your specific string. register the license code within your specific framework's startup file? syncfusion unlock key link