Any minor 12 years of age or older may voluntarily submit himself to treatment for drug dependency as defined in N.H. Rev. Stat. § 318-B:1, IX, or any problem related to the use of drugs at any municipal health department, state institution or facility, public or private hospital or clinic, any licensed physician or advanced practice registered nurse practicing within such nurse practitioner‘s specialty, or other accredited state or local social welfare agency, without the consent of a parent, guardian, or any other person charged with the care or custody of said minor. Such parent or legal guardian shall not be liable for the payment for any treatment rendered pursuant to this section. The treating facility, agency or individual shall keep records on the treatment given to minors as provided under this section in the usual and customary manner, but no reports or records or information contained therein shall be discoverable by the state in any criminal prosecution. No such reports or records shall be used for other than rehabilitation, research, or statistical and medical purposes, except upon the written consent of the person examined or treated. Nothing contained herein shall be construed to mean that any minor of sound mind is legally incapable of consenting to medical treatment provided that such minor is of sufficient maturity to understand the nature of such treatment and the consequences thereof.