Can you measure the still images (JPG, BMP) by MeasurePRO, MeasurePRO-Ex which taken by another company’s USB Microscope?

It is possible but also conditional.
It is conditional on the still picture shot by another company’s USB microscope that the object which becomes distance reference is reflected. It is possible to calibrate and measure it. By contrast, if there is nothing to be the reference of the distance, it will be difficult to calibrate because calibration is difficult.
Since our software can read still image data in JPG, BMP format. The measurement is possible if it meets the above conditions.