Registration is not optional for anyone marketing a registered project. What the Act expects of an agent, and the paperwork worth keeping.
The Real Estate (Regulation and Development) Act came in to put a floor under how property is sold in India. Most of the attention went to what it asks of developers, but it also asks a great deal of the person who introduces the buyer.
Registration is the first of it. An agent who facilitates the sale or purchase of a unit in a registered project is expected to be registered with the authority in that state, and to quote that registration number in the paperwork. Registration is state by state, so working across a border usually means registering twice.
The second is record keeping. An agent is expected to keep books of account and to be able to show what was represented to a buyer and when. In practice this is the part that protects you. A file with the agreement, the receipts and a dated note of what was promised is the difference between a dispute and an argument.
The third is the plainest and the easiest to breach: do not make a statement about a project you cannot support. That covers approvals, timelines, amenities and carpet area. If a developer's brochure says it and the sanctioned plan does not, repeating it is your problem as well as theirs.
Rules, fees and renewal periods differ by state and are revised from time to time. Check the current position with the authority in your own state before you rely on any of the above.