No, LifeLock does not prevent anyone from using your existing accounts. However, those accounts would be covered through the guarantee. Through the information you provide, LifeLock will alert you when anybody other than yourself tries to open new lines of credit. LifeLock suggests you place all your account numbers in a secure place if your wallet or purse is stolen. In such a case give LifeLock a call and LifeLock can help contacting the credit card companies to cancel the stolen cards and reissue new ones.