Section 7. Any person residing in the commonwealth who meets the qualifications specified in the by-laws of a medical service corporation shall have the right to become a subscribing member of the corporation. No officer, agent or employee of a medical service corporation shall influence or attempt to influence a subscribing member, or his dependent, in his choice of an associated physician. Any medical service corporation may, at its discretion, deny the right of membership to any person who makes any fraudulent claim or representation to the medical service corporation or associated physician or who has failed after a reasonable period of grace, to pay dues or other charges as provided in the subscription agreement, or for any other cause which may be approved by the department of public health.