Hi there,
I have some idea about your internet cafe business. I didn't know if this cafe runs with dedicated computer or just setup with wireless thing that can connect for mobile devices only (i.e mobile phones, laptop), but let's figure it out. At first, we can try to configure a
Hotspot which you can set the profile for the expires session within how long would be, could be in daily, weekly or even monthly. Then, there's some routerboard that support
UserManager for RADIUS server to create a voucher if we wanted to be printed or something. But, for the mechanism to charge and automatically active the users internet back again after payment, for me still no idea. I have same situation long before and I used to activated the expiration back manually after the users pay the bills.
I suggest you to read further more on this manual about what I'm saying above:
Sorry for my bad grammar, hopefully this find as a solution that could help your situation, let's learn together and correct me if i'm wrong