Keil Logo

LICENSE: Issues with Licensing a Product Serial Number (PSN)

Information in this article applies to:

  • C51 Version 8.00 and later
  • C166 Version 5.00 and later
  • CARM All versions
  • MDK-ARM All versions


When following these steps for license registration, the Keil webpage gives the following error message:

Problems were detected with the information submitted. Please correct these issues and re-submit the form.

  • The Product Serial # (PSN) entered is invalid.

I'm using the number printed on the CD package I received, or from an email, or from a card. What am I missing?


For all ARM Versions, C51 version 8.00 and later, and C166 versions 5.00 and later, you must register your computer using a License ID Code (LIC) number instead of the Product Serial Number (PSN). Previous versions of the tools used a Serial Number and an add-on disk for licensing - this Serial Number will not work in the newer version of the tools.

One person may install the tools and use their PSN to get LICs for up to 2 of their computers. You may unlicense a computer to move the license to another computer. Unlicensing a computer frees up one of these seats.

To download the software, please go to Download Products, and in the blue box at the bottom of the screen, paste in your 15-digit Product Serial Number (PSN) - this alphanumeric code is in a XXXXX-XXXXX-XXXXX format.

Do I have a FlexNet License?

  • Take a look at your PSN. If the middle group of 5 digits (XXXXX-nnnnn-XXXXX) are are all numeric, you have a FlexNet license.

Troubleshooting: If the website does not recognize your code:

  1. You may have not entered the PSN correctly; try changing the letter O to a number 0, etc.
  2. You company purchased a FlexNet license, not a single-user license. For customers with FlexNet licenses, use the special download-only PSN found LICENSE: How to download MDK-ARM with a Flex license to download MDK-ARM products.

If you have not yet obtained an LIC number...

FlexNet License

Single User License

  • Follow these steps to activate a single user license for your computer.
  • You will receive e-mail with a 30-digit LIC code. Use this LIC code to register your product.
  • If you have issues entering the PSN on the form, your PSN may have a Floating License File (FLF) user license.

Floating User License

  • Follow these steps to activate a floating user license for your computer.

Make sure you add your new License ID Code into the License Management dialog in order to activate the full version of the software. Without a valid license, the software will behave like an evaluation copy.

In case you need to re-register, keep track of which email address you used to register for a LIC.



Last Reviewed: Thursday, August 29, 2019

Did this article provide the answer you needed?
Not Sure
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.