Calibrating Garmin Virtual Run

I’ve bought a Garmin Fenix 6 to link direct to Zwift using the virtual run option. The first time I used it I did the calibration option when pairing the device and the run that followed was relatively accurate between the watch and treadmill distance.

Does anybody know I need to do this each time or will Zwift memorise the calibration? I’m not convinced it would know how to store this calibration.

I’m also purchasing an NPE RUNN and again…would this need calibrating each run?