Do I need to open Vivace all the time to track my steps?

No – but it’s best to keep Vivace running in background mode. Vivace will wake up in the background when you walk more than 30 steps (approximately) and sync with Apple HealthKit. If you close Vivace completely, your steps will still get recorded in HealthKit, but Vivace won’t be able to sync and you won’t get any smart nudges.