is there anybody who has used it and gained some inches to their height?
While genes are the most contributing factors to height, a healthy lifestyle can help a person reach his or her potential height.
It is a scam.
You won't get taller using urea of any sort.
Their site refers you to Wilipedia - an article about nitrogen and growth, which states "More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer."
It might help crops grow but it will not affect human growth.
Tryptophan is more relevant, it's is an amino acid that is converted to serotonin, which increases HGH (Human Growth Hormone) during sleep.
It's a routine constituent of most protein-based foods or dietary proteins. It is particularly plentiful in chocolate, oats, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas, sunflower seeds, pumpkin seeds, spirulina, and peanuts.
Your height is determined by your genes, if your growth plates are closed not urea - or tryptophan - will make 'bones grow longer'