With Marshmallow, you’ll notice a new memory option inside the system settings menu.
Select from the past 3 hours, 6 hours, 12 hours, and 1 day.
From here you can see average memory use. If the performance is showing something other than Normal, such as critical, you might experience system instability.
If you see memory becoming an issue consistently, you can use this setting to discover if any particular app is having memory issues.
Select “Memory used by apps” to go in and see more detail. Select a particular an app, from there, you can see the frequency, maximum usage, and additional detail on how it is using the device memory.