One way to do this in v16.0, is to create a layout with a map in a frame and insert your legends in a frame on top of the map.
![MI Pro with Layout and Legend]()
In order to make this work nicely when outputting it to an image, I have set the paper size to 25 by 25 cm and set the margins to 0 via the Page Setup and then the Printer Properties (I used the MapInfo PDF Printer Driver)
![Printer Page Settings]()
And here is the final image save as PNG from the layout
![Map with Legend]()