Color by Numbers for Adults is a coloring book app available on iPhone that offers an extensive selection of pictures to color. With over 1000 free images from various categories such as Holidays, Food, Animals, and Landscapes, users can enjoy a new picture every day. The app also has two features that make the process of coloring easier: "Next shape for the color" and "Fill the shapes with the same color."

The app also offers a premium subscription with weekly, monthly, and annual payment options. This subscription unlocks all the pictures, provides new free pictures, removes ads, and offers unlimited hints and paint buckets.

One thing to note is that any unused portion of the free trial will be forfeited when you purchase a subscription. The app also collects personal information, and users are encouraged to read the EULA and Privacy Policy before use.

Overall, Color by Numbers for Adults is a great app for those who enjoy coloring and want a wide selection of pictures to choose from.