This is from the user manual
Demo mode
If you have not authorised Z3TA+ in the Cakewalk Store (or on Steam), Z3TA+ will function in Demo mode.
The following restrictions apply to Demo mode:
Z3TA+ will randomly output silence at different intervals.The About Box shows “Demo” instead of your username and serial number (click the Z3TA+ logo in the top
panel to open the About Box).