Rent Electrical Device by time management system

We would like to build system to manage Rent Electrical Device by time. Customers buy a card (magnetic or smart card) refillable and when use it in device it will work for #of minutes depends on the amount of minutes in card. For example I’ll refill card for 120 minutes I can use it many times until my 120 minutes finish, each time I use it only the exact # of minutes will be deducted from the card. System from 2 main parts 1- PC software to manage cards and refill. 2- Card reader with relay controller to open relay until # of minutes in the card finish. Need: 1- Relay control circuit driven by microcontroller to read # of minutes in the card and deducted the minutes while the relay is open when card removed or balance finish the relay switched off 2- PC software to refill cards. Enter # of minutes and read card balance. Please review this project, asks if you need more info, make your bid with description what you will do. Thanks.