As the trial period was just started I can not really test what happens after the trial ends. What I understood is that you can still open the mockups in a read only mode, but is it possible to comment the mockup in anyway after the trial has ended?
You’re right, @nsika, that is the current behavior indeed. Once the trial expires, you still have access to viewing your wireframes via our Full Screen Presentation mode.
That being said, we will look into changing this so that everyone could access the new Review and Comment mode in our new product: Balsamiq Wireframes for Google Drive.
I’ve added your vote for this already!