The features in the free version are pretty basic, but still useful, in my opinion; the main downside is that the pop-up ads for the paid versions come up frequently, which gets irritating; on the positive side, you can "donate" the gems you earn to a dog charity (in other words, you can have the developer will donate money in your honor) without spending any money. Pro Plus has more useful features, such as adding up to 10 custom tags for time tracking, and getting the optional anti-cheat mode (the donut machine stops if you leave Focus Dog or open another app).