Do anyone have any updated idea by when one should leave the country in what time duration after receiving approved for visiting visa at nepal. It heard the the person has to fly within 6 month even after the visa gets approved for 5 years.

Does any one have any idea, my relatives had received visiting visa for 5 years, but just curious to know by when they have to leave there and if they do not leave withing 6 month, what is the process to come again?