SAPGUI NTLM SSO licensing

Is there a licensing involved when using NTLM SSO specifically documented in this URL Single Sign-On with Microsoft NT LAN Manager SSP - User Authentication and Single Sign-On - SAP Library? 

Is there documentation anywhere referencing licensing or no licensing using this SSO method?

If there is licensing involved, are there any free SSO licensing schemes available for SAPGUI?

Thanks

Regards,

Mel Calucin