With a Fi Subscription/Membership, you gain access to the full capabilities of your dog's Fi Collar. The subscription/membership cost covers the GPS/LTE connection when your collar is unable to connect to Wi-Fi, your Fi Base or your smartphone's Fi App. A subscription/membership allows for remote access to your dog's location, activity and Lost Dog Mode.
With a Fi Subscription/Membership, as long as your dog is in the United States, there is GPS and cellular (LTE) coverage, there is no limit on how far Fi can track your pup!
To check coverage before you purchase, see: How Will I Know If the Fi Collar Has Cellular Coverage in My Area?