Hi
pankajpaikra1503Thank you for your asking. First, please note that unlocking the device or flashing the custom ROM are quite risky, may causing security issues like Widevine Issue, banking app usage issue, or unexpected software issues. Second, any unlocked/rooted/custom rom device will be regarded as out of warranty device, revised device. Last, officially, we do not provide lock back service/tools. Once the device is unlocked, the server will have related record and it can never be revised even if you lock the device back by yourself.
For more information, please check the picture as the release notice of Unlock boot loader on our official website. Thank you.
https://www.asus.com/supportonly/ZenFone%20Max%20Pro(M1)(ZB602KL)/HelpDesk_Download/