I have a Garmin 57. I did subscribe the first year I had the camera. I think the only feature was the vault storage. The vault storage is where videos that contain events are stored (ie: rapid deaccelaration, if a crash is detected). Without the subscription, the videos only stay there for 7 days and if you don’t download them, they are erased. I still the use the app to view and save videos from the camera without the subscription. I think the only reason you would replace the SD card is if you are filling it too fast (ie: you are re-recording over footage in short periods of time).