There is no mention of extra fees on this attachment taken from their website

Hi there, I had replied to your another post at https://forum.dji.com/forum.php? ... p;extra=#pid2491496, a small additional fee will be required for using DJI Care Refresh, please check the whole description for the details. Hope your kind understanding.

it's super transparent when you sign up for the service. also in the terms and conditions!