* According to my knowledge, live-in-relation is allowed by supreme court and adult couple can stay together whether it is a hotel, home, or rented house.
-: Yes you are correct; live in by adults are legal, with the following correction.
* Can a couple (18+) stay in a hotel without marriage?
-: Yes; with a little correction, the lady must not be a married one but the male, may or may not be.
* What to do if after taking room someone threatening that they will inform to police.
-: Everyone has the right to inform police whenever he/she saw/witnessed an offence, what is there? Here question is whether you are doing an offence? If no, then ignore the so called threat.
-: The problem comes from another side; the hotel management afraid that the case might be a case of prostitution, which is illegal (renting premises for this purpose). To resist it they sometimes refuse to accommodate the couple. Therefore sufficient identity proof, age proof, residence proof and your job proof should be along with you and your partner. Some dalal type people took interest for snatching money from the couple, ignore them.