Hi @srifat and welcome to the forum.
NegativeLab Pro delivers results that are way better that what I’ve seen in other pieces of software that offer negative conversion at reasonable prices, therefore I can understand the interest in a stand-alone version or plug-in for other apps.
NLP is built around services that are provided by Lightroom and by Lightroom alone. If NLP were to work standalone, much effort would have to go into it, be it in work hours or specific know-how and the same same is true if it were to work as plug-in for, multiplied by the number of photo apps that people use.
@nate has commented on the topic a few times and you can find his posts throughout the forum.