I am not completely sure, but it appears to be a one-time charge for an initial three-year subscription. I have no idea whether GM is also making some not-quit

I am not completely sure, but it appears to be a one-time charge for an initial three-year subscription. I have no idea whether GM is also making some not-quite-essential but both simple and useful features only accessible with an ongoing subscription, but I have my opinion as to whether it will do so, if it is not doing so already. Plenty of other manufacturers do this.