— used to describe a system of payment in which bills are paid when they are due or goods and services are paid for when they are bought（账单）到期即付的；现购现付的
The city adopted a pay-as-you-go policy to avoid future debt.市政府采取现购现付的政策，避免将来出现债务问题。
I use a pay-as-you-go plan for my cell phone.我的手机用的是定期打多少付多少的话费支付方式。