they won't work if you discontinue using it..the glow will not be permanent. they have harmful ingredients.  even carcinogenic ingredients. i can suggest some home remedies. and a few creams. 

Fairness creams have bleaching agent in them and you must know bleach is harmful for our face for long term. Don’t believe in these fairness creams because they cannot help you reduce the melanin content in your body! 🤷‍♀️

I suggest you not to.. instead you can rub lemon on your face twice everyday. Aloe Vera gel will also help. these fairness cream does give you glow but when you discontinue using it. your face will get back to being dull.. but if you've read positive responses on that cream then go for it. if you find the cream's ingredient list just dm me. I'll tell you bout it in depth. 

does anyone here knows about Khushi fairness cream by Rehnuma Khan. I have heard that it gives Glow to your face in just few days. but I'm confused whether I should buy it or not. please suggest.