Is widely approved to indicate at no financial Expense. Its use is suitable in promoting or speech and its use is recognized to signify no financial Charge. I would only alter the use in a very scenario where clarity and accuracy have been certainly important, like in a agreement. A https://drive.google.com/file/d/14hrpBHBebZB7SuXhV7sUnMwZIuxqpI1J/view?usp=sharing