Getting error "the remote session was disconnected because the Remote Desktop Client access license stored on..."

Good Day,

We have now had this error message occur on three Windows 10 Pro clients when trying to run an Remote App on our Windows 2012R2 RDS Farm. We have fixed the error on the client by:

1 renaming the reg key HKEY_LOCAL-MACHINE\SOFTWARE\Microsoft\MSLicensing to .bak and then

2 running regsvr32 mstscax.dll

My question is why is this happening? We are not low on Windows 2012R2 licenses.

Steve J.