Upgrade from Windows 10 LTSB to LTSC

We bought a Panda with a Windows 10 LTSB license. Activation of the license that came with it went smoothly. When we upgrade it to the newer LTSC version, it appears that the license became invalid since it now wants me to activate after it was upgraded. Has anyone else been successful doing this?

I found this link: https://social.technet.microsoft.com/Fo ... itprosetup

It seems to indicate I need access to a KMS server since it shows me as a VOLUME_KMSCLIENT