Applying IronPDF License Key to Projects

Curtis Chau

Updated: August 26, 2026

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  # Applying IronPDF License Key to Projects The license key is a long string that ends with the license support expiry date. Please ensure this is copied correctly. ```txt IRONPDF-MYLICENSE-KEY-1EF01-EXPIRES.01.JAN.2050 ``` Any additional spaces or characters in the license key string will result in the following error: ```txt Unhandled exception. IronSoftware.Exceptions.LicensingException: IronPDF must be licensed for development. ``` The most robust method of applying a license key is directly in your code, before the library is called. ```cs // Set the license key for IronPDF before making any calls to the library. IronPdf.License.LicenseKey = "IRONPDF-MYLICENSE-KEY-EXPIRES.01.JAN.2050"; ``` [[i:(Starting from IronPDF version 2024.1.20 onwards, users are required to have at least a free [trial license key](trial-license) in order to use the IronPDF library in their projects. Absence of a license key in the project will result in a watermarked PDF.)]] For more options, including `web.config` and `appsettings.json`, please see the following how-to page for more information: [IronPDF License Keys](/get-started/license-keys/)

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The license key is a long string that ends with the license support expiry date. Please ensure this is copied correctly.

IRONPDF-MYLICENSE-KEY-1EF01-EXPIRES.01.JAN.2050

IRONPDF-MYLICENSE-KEY-1EF01-EXPIRES.01.JAN.2050

Any additional spaces or characters in the license key string will result in the following error:

Unhandled exception. IronSoftware.Exceptions.LicensingException: IronPDF must be licensed for development.

Unhandled exception. IronSoftware.Exceptions.LicensingException: IronPDF must be licensed for development.

The most robust method of applying a license key is directly in your code, before the library is called.

// Set the license key for IronPDF before making any calls to the library.
IronPdf.License.LicenseKey = "IRONPDF-MYLICENSE-KEY-EXPIRES.01.JAN.2050";

// Set the license key for IronPDF before making any calls to the library.
IronPdf.License.LicenseKey = "IRONPDF-MYLICENSE-KEY-EXPIRES.01.JAN.2050";

' Set the license key for IronPDF before making any calls to the library.
IronPdf.License.LicenseKey = "IRONPDF-MYLICENSE-KEY-EXPIRES.01.JAN.2050"

' Set the license key for IronPDF before making any calls to the library.
IronPdf.License.LicenseKey = "IRONPDF-MYLICENSE-KEY-EXPIRES.01.JAN.2050"

For more options, including web.config and appsettings.json, please see the following how-to page for more information: IronPDF License Keys

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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