procedure TForm1.FormCreate(Sender: TObject);
begin
 RegExp:=TRegExpr.Create;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
 tag:string;
begin
 regexp.expression:='<lol>(.+?)</lol>';
 tag:='<lol>Hello world</lol>';
 if RegExp.Exec(tag) then showmessage(RegExp.Match[1]);
end;