That Sprint service isn't offered because it's totally unnecessary if you have an Android phone and a Gmail address. Even if you lose, break, exchange, factory reset or replace your Moment, (I've done both of the last two) you can get your contacts back as soon as you set up your Gmail account on the phone because it will auto sync the contacts with the newly set up Gmail account. Then, to keep your contacts updating, you must go to Data Synchronization and check Background data and then contacts. If you do this and leave them checked, it will regularly automatically update your contacts, but that will suck down battery power too. Instead, every once in a while going in and checking them manually and then unchecking both when finished will keep contacts updated while saving lots of battery life.
Also, your contacts, which are also stored as part of your Gmail account, may be updated using your phone by syncing your contacts after editing them OR by editing your contacts in Gmail under contacts and then syncing the contacts. Hope that clears up any issues with contacts,