Photo Pro offers a useful tool for coloring and graying photos, but is in many ways limited by its trial restrictions. While the core functionality that the free app comes with works well, it's not enough to replace other photo editing apps that do this and much more. As a result, you may find the app lacking in several key areas if you want to do anything more than change the coloration of a photo on your phone.
When you open Photo Pro, you can choose to either load an image from the gallery or take a new one with your camera. Afterward, you can load up the editing tools and start modifying the image. The default mode is to change the photo to grayscale so you can paint any parts of it you want to be in color. Just wipe your finger over those areas to convert them from black & white to color. Switching between black & white and color is easy, as well, though other options like effects, frames, and text are all locked, pending a paid upgrade.
The interface is relatively straightforward, the color alterations work quickly and effectively, and the app exports nice-looking photos and can share to social media, easily, but unless the only tool you need is color to grayscale and back, Photo Pro is limited in its free iteration.