I just wonder how the payment process goes if I pre-paid $5 with Paypal (without Credit card), and it uses up the $5.
If I don't want to pay from the credit card, what should I do?
Maybe I could pre-paid again?
Also Can I choose how much I could pre pay?
When using paypal as your only payment method the services are offered on a pre-paid basis. Since your billing amount is based on your usage in a given month we are not able to offer a paypal subscription option. You can set an alert in the control panel to let you know once your usage reaches a point you specify but you are ultimately responsible for ensuring that you make payments as needed to maintain credit on your account.
If your credit is used up your droplets will continue to incur charges but will not immediately be deleted in order to give you time to make a payment but if a payment is not received within a reasonable time your account will be suspended and your droplets may be at risk of deletion.