Algorithm for a membership plugin

I want a to build a membership plugin.But i don't think a plugin like that is available if so please tell me

else

please guide me and give me some direction that how do i proceed

There will be a login for members.Based on membership (Golden,silver,platinum) one will see the available services like

service 1 -> 50 instances
service 2 -> 20 instances

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service n ->n instances

A person will be able to book the service and manager gets the notification at the backend. Now if the person avails the service, the manager can strike out the services . For example if a person avails the service 1 , then remaining instances for service 1 will be 49.

Please guide me a bit , i will be really grateful