how to mount NAS permanently as drive even after reboot without root login?

Solution 1:

       password=arg|pass=arg
              specifies the CIFS password. If this option  is  not  given  then  the  environment
              variable  PASSWD  is  used. If the password is not specified directly or indirectly
              via an argument to mount, mount.cifs will prompt for a password, unless  the  guest
              option is specified.

              Note that a password which contains the delimiter character (i.e. a comma ',') will
              fail to be parsed correctly on the command line. However, the same password defined
              in the PASSWD environment variable or via a credentials file (see below) or entered
              at the password prompt will be read correctly.

Use : credentials=/path/to/file instead of the userrname=...,password=...

       credentials=filename|cred=filename
              specifies a file that contains a username and/or password and optionally  the  name
              of the workgroup. The format of the file is:

                 username=value
                 password=value
                 domain=value

              This  is  preferred  over  having  passwords in plaintext in a shared file, such as
              /etc/fstab . Be sure to protect any credentials file properly.

That should work on boot. - At least it does for a couple of my Servers in various locations and setups.