If you wan't your customer to be free to decide when to log off and pay you after use then the postpaid downloads are perfect for you. This option additionally contains contracts which are prepaid. Contracts assist you to preserve your loyal customers by preselling bulk time to them e.g. 5 hours and giving each customer a username and password that they will come back and login with on any free PC time and again, without disturbing you at the counter, until they get a warning to either buy more time or be logged off.
If you wan't to ask your customer to anticipate how long he/she will be using your pc and thus pay you before use, and get a warning when the time is almost up that he/she must either buy more time otherwise be logged off shortly then the prepaid downloads below are perfect for you. For your loyal customers, meaning those that come again and again, the contract option described in the postpaid above is also available in this prepaid option. The difference between the contract and normal prepaid is that it takes 2-3 seconds to issue a normal prepaid password where as it takes a once off 1-2 minutes per new contract customer to create a contract because you have to collect customer name and last name, issue a username and password etc. So contracts although very efficient end up being practical and cost effective for returning customers (in other words loyal customers or regulars) and normal prepaid ends up being practical and cost effective for the rarely returning or once off, never returning customers.