Android 8.0 requires all applications running in the background to inform users with a notification. So, whenever Walkr is running in the background, you'll see this notification pop up without the option to dismiss it. (If you get rid of the notification, Walkr won't be able to track your steps!)

On the other hand, since Walkr has to run in the background to be able to track your steps, you can think of this notification as an indication that Walkr is functioning properly on your Android 8.0 phone! So long as you see this notification, your steps are being counted. If you suddenly don't see this notification anymore, it means Walkr is no longer running in the background. You'll have to re-open Walkr to get the step tracker running again.