When i’ll get my Chips i must set a password with DT app or Is It Just recommended ?
Which chips are you getting?
For example
The NExT implant comes with a password already set.
It is not really a password in the traditional sense, because somebody 
has kindly set it up for you, to protect you from yourself. (if you decide later you want to change/ remove it, you can, most people won’t / don’t, including experienced users)
It’s not a password that you use to get access to the functionality.
The NExT will work right “out of the box” so to speak.
In saying that,
The xNT does not have a password set, but will also work out of the box.
The Dangerous things NFC App protects the implant from somebody accidentally or maliciously locking it.
Some would suggest using it, some wouldn’t
The choice is yours