If you are trying to use a version of DevExtreme released after the expiration date of your license key, the browser displays a warning in the console（license mismatch）. You can either downgrade to a version of DevExtreme you have licensed in the past or renew your subscription to obtain a new license key.

This is the most misunderstood aspect of the DevExtreme license key.

Having a valid DevExpress license key offers numerous benefits, including:

Then import it in your main.js or index.ts any DevExtreme component.

For pure client-side apps, the license key is injected via a JavaScript configuration file, typically license.js or in your main entry file (e.g., main.ts for Angular).

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public void ConfigureServices(IServiceCollection services)

Or inject it during the build step.

Mixing DevExtreme and another DevExpress product (e.g., Reporting) with different license keys. Solution: Use the Universal key for all. If you have separate keys, apply the most permissive one last.