text: function BtnConstruct() {  
    this.change_button = function() {
      var btn = $("#agree_with_terms");
      
      if ($('#_terms_of_use').prop('checked')) {
          btn.removeProp("disabled");
      } else {        
          btn.prop("disabled", true);
      }
    };
  }
  
  jQuery( document ).ready(function() {
    var inst = new BtnConstruct();
    $('#_terms_of_use').click(function(){
      inst.change_button();
    });
    inst.change_button();
  });