Adding items to Subscription Package in WordPress

Question

I have a small challenge. The bigger problem is that I don't know how to go about it.

I want to make a WordPress Courier Website with Subscription Option and item tracking.

For the subscription part, say customer A subscribed to Gold Package. I want Gold Package to have 20 item deliveries per month.

Now, when a Delivery is made, I want to be able to deduct each delivery initiated by customer A from the 20 items in that Package till it is exhausted.

And once it’s exhausted, the customer should be charged at a fixed price.

How can someone make a website like this in WordPress?

Which plugins exist that makes something like this possible?

Regards