Nordvpn installed, but If I restart the WD I need to reinstall it!

Do you have any apps installed, e.g. phpMyAdmin, entware or transmission?
If yes, look up the init script

find /shares/Volume_1/Nas_Prog -maxdepth 2 -name init.sh

Put all the required steps to set up NordVPN in a script.
Then modify one of the init script you found earlier to run this script.
Done.

If you share the modifications you used to setup NordVPN, I may provide more details.

EDIT: I quickly looked it up. Based on this tutorial

  1. Download the ovpn file of your choice.

  2. Copy it to the directory containing the init script

  3. Add a credentials file to the same directory with these 2 lines

    myusername
    mypassword

  4. Edit your ovpn file and link to this file

auth-user-pass /shares/Volume_1/Nas_Prog/transmission/credentials
  1. Add these lines to the transmission init.sh script. Note the trailing ampersand.
APPDIR="$(dirname $0)"
openvpn.bin ${APPDIR}/wherever.nordvpn.com.udp1194.ovpn &