# Obtaining a license key

The open-source Saxon-B product does not require any license key. For Saxon-SA, however, you need to obtain a license key from Saxonica. You can order a free license key for a 30-day evaluation, or purchase an unrestricted license key from the Saxonica web site.

You need to specify when ordering a license key that you intend to use Saxon on the .NET platform, because the license keys are not compatible between the two platforms.

The license key will arrive in the form of a file named `saxon-license.xml` attached to an email message. You need to copy the file into the `/bin` directory containing the Saxon DLLs.

So that Saxon can find the license key, you need to set the environment variable `SAXON_HOME` to the directory where Saxon is installed: for example `set SAXON_HOME=c:\saxon`.

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