Hi Chris,
If she was using Windows 10 Enterprise, she can only upgrade it to Windows 11 Enterprise NOT Windows 11 pro as that will not accept the old license. Please ensure that when we upgrade any machine from Windows 10 to Windows 11, we should install the same version to avoid license conflicts. If the old license was valid, it doesn't matter it her old company was dissolved/closed or not, the license should still be active.
On the other hand, we can purchase Windows 10/11 license from Microsoft Store using any device. However, please ensure that you use a Microsoft account to sign in to 'Microsoft store'.
Please update with your findings!
Sincerely,
CK