No, the Lark app does not have to be open to track your activity. Once you begin using your Lark application, you will be prompted to grant Lark access to your phone's motion sensors.
On Android devices, you will be unable to begin your program until you grant Lark access to your phone's motion sensors. On Apple devices, this feature can be enabled or disabled manually, but we recommend keeping it enabled to allow for the most accurate assessment of your activity.
Once this access is granted, your activity data will be automatically saved in the background of your phone without the app needing to be open. Because Lark uses motion sensors to track your activity, we recommend bringing your phone with you when exercising so your activity is automatically logged within Lark.