Hide Course price for students who've already taken the course

add_filter('wplms_course_credits','wplms_hide_course_credits_for_course_students',10,2);
function wplms_hide_course_credits_for_course_students($credits,$course_id){
  if(!is_user_logged_in()){
    return $credits;
  }
  $user_id = get_current_user_id();
  if(wplms_user_course_check($user_id,$course_id)){
    $credits = 'Subscribed'; //hide credits for course students and display "Subscribed" message
  }
  return $credits;
}