Since the introduction of the pro version a banner advertising the pro version is shown every time a new file is opened or when you switch tabs to another file in the free version.
But many users will not need/want the pro features. There is no way to stop the banner nagging however, making the free version almost impossible to work with. Especially when using page/tab turner pedals since you have no free hands.
I suggest adding an option "No thanks" or "Keep using the free version" to the banner and, when this is selected, only showing the banner again when trying to use a pro function.