I recently upgraded to Zoho Assist Professional. Once I upgraded, I started receiving an error message on my unattended PC's when I attempted to change monitors; "You're currently in free edition. Upgrade now to access this feature." 

I contacted Zoho Assist support and received this reply.

      We had a breakage in our features earlier due to which the Send CTRL+ALT+DEL and the multi      Monitor navigation options were also available for the Unattended Access computers in limited features. That is the reason why you had access to these features until now. Our developers had analysed this breakage and a fix was rolled out yesterday to prevent access to these features. That is the reason why this option is not available for you. 

       To be able to access the Multi Monitor navigation option when connected to Unattended Access computers please upgrade to the Unattended Access Standard plan for the number of computers that you need.

Sounds like Zoho is making an excuse to charge customers more for something I had before the "break".