In California an unlicensed individual can be paid a referral fee for simply introducing a buyer - but that is it. If the unlicensed individual performs any activity aside from a simple introduction, such as negotiating of price/terms of the sale, marketing property etc., then that Individual is performing "licensed activity".
The California Department of Real Estate issued a bulletin (page 3&4) addressing this topic including the 1995 legal opinion issued regarding finders fee for unlicensed individuals. This is the pertinent text:
"One question that is often asked is if a broker can pay a referral fee to an unlicensed person. The answer is yes if that person has not performed any licensed acts in connection with the transaction for which
the fee is being paid.
In 1995, the California Attorney General issued an opinion (78OPS CAL ATTY GEN 71) that stated a real estate broker can pay a commission to an unlicensed person for providing the name, telephone number and address of a prospective borrower provided that the unlicensed person did not obtain the information in the course of soliciting borrowers or lenders on behalf of another or others. The opinion also stated that the finder's exemption can only apply if the activity is limited to arranging an introduction between the parties and the unlicensed person cannot be involved in any role in the negotiation of the loan, no matter how slight.
Also:
The California Assoc. of Realtors there has a "Legal Memorandum regarding referrals, rebates and related arrangements under State and Federal law."
On page 7:
Question: "Can a licensee provide a finders fee to a non-licensee for referral of business?"
State law : " YES a licensee may pay such a fee if the non-licensee merely provides an introduction of a principal to the licensee. If the non-licensee is involved in more than the mere introduction of the parties and actually participates in the negotiation of the transaction, then such a fee would constitute an unlawful payment of commission to a non-licensee."
Federal Law: NO, if the transaction fall within RESPA." (RESPA involves settlement services)
"RESPA generally prohibits anyone from giving a fee, kickback or thing of value pursuant to an agreement for referral of settlement services in a sale of one-to-four residential units involving a federally related mortgage loan."
"settlement services" is later defined in the memorandum as "Title searches, Insurance, Broker services, preparation of documents, escrow and pest control activities".
See also this excellent treatment of the topic. http://www.brewerfirm.com/articles/article-splits-kickbacks-fees.html
The issue of Options and "Equitable interest" is not covered in the above. It's not necessarily a free pass in every state. (http://realestatecounsel.net/tag/equitable-interest/) At least in California according to this case, Equitable interest is not automatically conferred by an Option to purchase. In fact the particular case discussed casts at least some doubt on it. The mere fact that someone is not on title marketing a property is likely to eventually draw unwanted scrutiny and legal hassles.