Honeywell thermostat which comes with lock mode are Honeywell Pro series and 8000 series thermostats. These thermostats will operate on password .Many Honeywell thermostats comes with default password 1234.These password can be changed. They have basically 2 lock mode  one is partial lock and other is full lock. In partial lock, user can access the thermostat  partially means they can change the temperature manually . Where as  full lock  will completely lock the thermostat .You can not change anything until the correct password is not entered.