will phone lock up with a hard reset?

So I just got an unlock code for my torch and I'm wondering would a full reset meaning delete eeevvveerything lock up the phone again or once unlocked it doesn't lock up again no matter what? Thanks

Once a phone is unlocked, it's unlocked for good.

Thank you sir!

What happens when you update the OS? I would imagine that you would have to remove the vendor xml file for AT&T.

The vendor.xml file tells DM what carrier the OS is from, and if it's not from your carrier, DM won't allow the install. While this usually only happens with official releases (vendor.xml files with leaked OSes are usually blank), it's a good practice to always delete the file regardless, as it's usually the #1 culprit in installation issues.

is there anyway to remove the "unlock" on the phone?

if i want to unlock a torch to use it in mexico,

should i master reset it before unlocking or after?? cause it has the email and some other accounts from the previous guy.

and how do i erase the att books and download the telcel books?

anything else i should know ??