lock/unlock, how do you know?

[Caliburno]

I have recently bought a 2nd xt926 and just found it has the 183.46.15 ROM number
AFAIK is a locked and non unlockable bootloader version BUT
I have read that AFTER unlocking the bootloader and putting a new rom, you can put anything and your phone will never go back to locked again.

Is this right or am I wrong?

Is there any chance my new phone is flashable? How to know?

Thanks for your time.