Non-transitory computer readable medium for control program, control method and communication terminal

A control method for an in-vehicle device by a communication terminal having an input unit and a memory, comprising:

• a reading step of reading registration information indicating registration status of the communication terminal with respect to the in-vehicle device from the memory;
• a reception step of receiving a change instruction input via the input unit for a setting item of the in-vehicle device;
• and
• a restriction step of enabling or disabling input of the change instruction or the acceptance of the change instruction based on the registration information.

A communication terminal comprising:

• a microprocessor,
• an input unit configured to be operated by a user and capable of inputting a change instruction for a setting item of an in-vehicle device;
• and
• a memory connected to the microprocessor and storing, in advance, registration information indicating registration status with respect to the in-vehicle device, wherein
• the microprocessor is configured to perform:
• receiving the change instruction input via the input unit;
• and
• enabling or disabling the input of the change instruction or the acceptance of the change instruction based on the registration information.