niLicense: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/niLicense - from package: openni

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/niLicense - from package: openni-utils

You may install the required package with command apt-get install {package}

Error in other languages:
niLicense: bevel nie gevind nie
niLicense: comandă negăsită
niLicense: comando não encontrado
niLicense: commande introuvable
niLicense: command not found
niLicense: käsku ei ole
niLicense: không tìm thấy lệnh
niLicense: komanda nerasta
niLicense: Kommando nicht gefunden.
niLicense: kommandot finns inte
niLicense: komut yok
niLicense: nie znaleziono polecenia
niLicense: níor aimsíodh an t-ordú
niLicense: no se encontró la orden
niLicense: no s'ha trobat l'ordre
niLicense: opdracht niet gevonden
niLicense: parancs nem található
niLicense: perintah tidak ditemukan
niLicense: príkaz nenájdený
niLicense: příkaz nenalezen
niLicense: команда не найдена
niLicense: командата не е открита
niLicense: 命令找不到
niLicense: コマンドが見つかりません