Elementor Pro has been installed and activated – but Elementor is still telling me to “go pro” in the page editor. I purchased it so I could place a background image in the background of the page body of a secondary page. I do not see how to achieve this effect.
Did you deactivate the free version? Chances are you are using both at the same time :).
One thing I need to mention here is that Elementor is a third party plugin and we have no affiliation with the company. It is developed and maintained by a different company.