How can I add home network internet logon?

[blackmuttracing]

I am installing a "home network" in our fire station. I have a typical motorola modem with local cable internet, a D-Link 24 port switch, a buttload of CAT6 cable, and jacks/plates for each room. Now, how would I add internet logon so only the guys who paid for their internet could have access? (like at hotels that still charge for internet access). obviously we will all be chipping in $5 each month to pay for the access. Any other suggestions on network layout would be helpful. Thanks