A method of managing user account data of a user, by means of a wearable device in communication with a host device, the wearable device comprising one or more sensors for detecting whether a wearable device is worn and detecting whether the wearable device has been taken off, the method comprising: detecting by the wearable device, that the host device is within a threshold distance from the wearable device; when the host device is within the threshold distance from the wearable device, pairing the wearable device with the host device or determining that the wearable device is already paired to the host device; receiving, by the wearable device, an alert of a sign-in event or a notification of a sign-in event from the host device while the wearable device is being worn, whilst the wearable device and host device are paired, the sign-in event corresponding to the host device being unlocked by a correct passcode or credential from the user; and determining, by the wearable device, whether the wearable device is in a trusted state, the trusted state being that the wearable device is currently being worn and that the host device is within the threshold distance from the wearable device at a time correlated with the sign-in event; whilst the wearable device is in the trusted state, establishing, by the wearable device, a session key and a verified communication session with the host device; receiving, by the wearable device, user account data from the host device during the verified communication session, the user account data comprising identifying information for a financial account of the user and authorization credentials; storing, by the wearable device, the received user account data in a storage medium of the wearable device, for providing a subset of the received user account data to a checkpoint terminal; whilst the received user account data is stored in the storage medium, periodically determining, by the wearable device using one or more of the sensors of the wearable device, whether the wearable device has been taken off; and in response to a determination by the wearable device that the wearable device has been taken off: automatically deleting, by the wearable device, the stored user account data from the storage medium; and automatically ending, by the wearable device, the verified communication session. detecting by the wearable device, that the host device is within a threshold distance from the wearable device; when the host device is within the threshold distance from the wearable device, pairing the wearable device with the host device or determining that the wearable device is already paired to the host device; receiving, by the wearable device, an alert of a sign-in event or a notification of a sign-in event from the host device while the wearable device is being worn, whilst the wearable device and host device are paired, the sign-in event corresponding to the host device being unlocked by a correct passcode or credential from the user; and determining, by the wearable device, whether the wearable device is in a trusted state, the trusted state being that the wearable device is currently being worn and that the host device is within the threshold distance from the wearable device at a time correlated with the sign-in event; receiving, by the wearable device, an alert of a sign-in event or a notification of a sign-in event from the host device while the wearable device is being worn, whilst the wearable device and host device are paired, the sign-in event corresponding to the host device being unlocked by a correct passcode or credential from the user; and determining, by the wearable device, whether the wearable device is in a trusted state, the trusted state being that the wearable device is currently being worn and that the host device is within the threshold distance from the wearable device at a time correlated with the sign-in event; whilst the wearable device is in the trusted state, establishing, by the wearable device, a session key and a verified communication session with the host device; receiving, by the wearable device, user account data from the host device during the verified communication session, the user account data comprising identifying information for a financial account of the user and authorization credentials; storing, by the wearable device, the received user account data in a storage medium of the wearable device, for providing a subset of the received user account data to a checkpoint terminal; whilst the received user account data is stored in the storage medium, periodically determining, by the wearable device using one or more of the sensors of the wearable device, whether the wearable device has been taken off; and in response to a determination by the wearable device that the wearable device has been taken off: automatically deleting, by the wearable device, the stored user account data from the storage medium; and automatically ending, by the wearable device, the verified communication session. automatically deleting, by the wearable device, the stored user account data from the storage medium; and automatically ending, by the wearable device, the verified communication session.