Invoke authentication with licensing servers to enable or re-enable your use of Excel Lab.


Excel Lab authenticates with Windham's licensing server for convenience and security. If you encounter issues with re-authentication, you will be able to manually invoke authentication my following the syntax as documented below in Excel's formula bar.

You can invoke Excel Lab's license authentication process anywhere in a workbook. You can even do this in a new blank workbook.

You do not need to save the workbook once authentication is successful.


The following describes the function signature for use in Microsoft Excel's formula bar.



Follow the on-screen dialog prompt to enter your username and password.



Your e-mail address registered with Windham Labs.


Your password, or unlock key code for offline use. The offline unlock key code is only available for yearly billing plans.




Credentials (username / password) and account successfully authenticated. Enjoy ExcelLab!

Invalid Credentials

Invalid username and/or password. Check for typos, try again.


Your account is no longer active.

Invalid Permissions

Your account is not permissioned for the product / feature.


Your account has expired.

Invalid Host

Unauthorized device. Each Excel Lab license is locked to a device.

Missing Credentials

No input for either username or password. Please try again.


To manually authenticated

  1. Open any workbook, or create a new (temporary) workbook.

  2. In any cell, type =XLABLICENSE() in the formula bar.

  3. Follow the instructions as described in the Syntax section above.

When successful, Excel Lab will store your license information within user-specific system files. You do not need to save the temporary workbook.

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