TeamViewer commercial use detected error occur

Hi experts,
During the install of TeamViewer I have selected the Commercial Use and it worked just fine for 3-4 connections. This message appeared on my desktop when I tried to use to connect with another PC from another country. Why I have this message on my desktop since I already selected the Commercial Use option? Do I really need to buy the license?
Thank you!

Commercial use
COMMERCIAL USE DETECTED
This software seems to be used in commercial environments. Please note that the free version may only be used for personal use.
Your session will be terminated after 5 minutes. Please check our web site for further information.
