1) Avoid a balance 2) Buy online 3) Compensate in advance 4) Cover the cost, up front 5) End a mortgage early 6) Gas pump option 7) Gas-pump verb 8) Get a subscription 9) Give money in advance 10) Modern gas pump notice 11) Pony up in advance 12) Pump option 13) Purchase in advance 14) Put cash up front 
• (v. t.) To pay in advance, or beforehand; as, to prepay postage.
Wireless services paid for in advance, as opposed to billing in arrears or postpay. In prepaid mobile billing, the call activity must be monitored in real-time so that the subscriber can be prompted to buy more call minutes. If the subscriber does not buy more minutes then the systems must eventually cut-off the call. Technical challenges limit the services available, such as roaming and international calling.
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Pre·pay' transitive verb [ imperfect & past participle Prepaid ; present participle & verbal noun Prepaying .] To pay in advance, or beforehand; as, to prepay postage. 
[v] - pay for something before receiving it
prepay 1. To pay for something before receiving it. 2. To pay in advance for goods or services.
to pay or arrange to pay beforehand or before due: to prepay the loan.