My Customer App is designed to store details of the customers and manage them too.
Where you can add new customer details and even update the details of your customer.
So you don't need to remember each and every detail about your customer. Just check the app to get the details about your customer like Total Amount to be paid, Amount paid, Amount remaining and Status. By this you can come to know which customer has paid you the amount and which hasn't.

New feature requests are welcomed.