Systems and methods are provided for controlling access to online services. For example, the system may include an application running on a user computer (130) that collects platform data (e.g. physical device parameters) and generates a machine fingerprint (stage 602). The computer (130) may send the machine fingerprint to the authentication server (110). The server (110) may associate the received machine fingerprint with the appropriate online account information received from a host server (120) or the like (stage 604). The authentication server (110) may send the appropriate registration status signal to the host server (120), which in turn may update the online profile information to include the user's registration status (stage 606).