Cancel Constant Contact Subscription if User does not Check the sign up box on more than one form.

functions.php

<?php
function disable_newsletter_signup( $form_id ) {
    global $ninja_forms_processing;
    $form_id = $ninja_forms_processing->get_form_ID();
    if (  $form_id == 1 || $form_id == 2 || $form_id == 3 ) {
      
      switch ($form_id) {
    	case 1: //Form 1 
        	$opt_in = $ninja_forms_processing->get_field_value( 32 );
        	break;
    	case 2: //Form 2
        	$opt_in = $ninja_forms_processing->get_field_value( 25 );
        	break;
    	case 3: //Form 3
        	$opt_in = $ninja_forms_processing->get_field_value( 14 );
        	break;
    	default:
        	break;
	  }
	  
      if ( $opt_in == 'unchecked' ) {
        $ninja_forms_processing->update_form_setting( 'constant_contact_signup_form', false );
      }
    }
}
add_action( 'ninja_forms_pre_process', 'disable_newsletter_signup' );