A device management system according to the present invention issues a register key that specifies a worker tenant, receives a registration request including the register key from a network device, and transmits first authentication information to the network device. The first authentication information is registered in the worker tenant that is specified by the register key of the registration request. If there has been communication that uses the first authentication information from the network device after the tenant is created, the information about the network device registered in the worker tenant is automatically changed to be registered in the different tenant.