No, only an actual licensed contractor can directly put a contractor's lien on a home. What he can do is sue you, however, if there was an agreement that you would pay him for his labor and you don't pay. However, if he had done the work as a gift, he is not entitled to money--only if there had been agreement that he'd be paid. Of course, he can lie and claim there was an agreement even when there was not: if he is willing to do that and sues, you can fight or defend on the basis that no, the labor was a gift. In that case, it will come down to who is personally more credible or believable; whose story makes more sense in the context of the facts and relationship at that time; who has more and more believable witnesses supporting him or her; and whether there is any documentation, including emails or text messages, supporting either him or her.