Assuming that the therapist is located in California and gave the advice to the friend in California, California law will determine whether the friend has a potential malpractice claim. (If one of those facts is changed, then a choice of law issue may arise). The fundamental legal issue is whether the facts support the conclusion that a therapist-patient relationship had been established. If so, then the therapist undertook a duty of care toward the patient, regardless of whether the friend paid for the advice. California Evidence Code Section 1011 addresses that issue. Your friend will need to consult a California attorney familiar with these concepts. Furthermore, California imposes relatively stringent time limitations for such actions, so your friend should proceed expeditiously.