The description page makes it sound like that's a paid-only feature. And it seems like the focus is on battery savings, so it is looking for applications using a lot of CPU rather than a lot of memory. If that app does have a history of memory usage per-app, that would be extremely helpful, though, sure!
The "History" feature is a paid feature. But you can monitor memory usage and cpu usage in real time in the free version. It's great for battery and memory troubleshooting which are my main concerns right now...