at-once payment

基本解释

Finally, guests can check-out from their mobile device at any time, even once they have left the property, settling outstanding charges via secure payment systems.
最後，客戶可以在任何時候通過手機結賬，甚至在他們離開酒店之後，他們也可以通過安全的支付系統來結算一些未支付的費用。
Make sure you have a payment schedule in place and make sure your clients understand when you expect to get paid. It could be once a month, up-front, upon completion or at a different set interval.
確定你有一份付款進程表竝確定你的客戶知道你希望什麽時候付款.可以是一月一付,可以是完工後付,也可以是某個間隔時間付.