Working of Billing Cycle in PSB

The billing date is set according to the first payment made. That means when the first payment is successful and the subscription is activated, from that day onwards the billing cycle will start for that subscription.
However, there can be 2 cases. Let's understand it here.
Case 1: Customer A, purchases a monthly subscription on 25th Nov with successful payment, and his invoice is also generated. Since his payment was successful and his subscription got active on the very day, his monthly billing cycle will be set as from 25th Nov to 25th Dec.
Case 2: Customer B, purchases a monthly subscription on 10th Nov, and his invoice is also generated but his first payment gets failed due to some reason. Now, he pays for that pending invoice after some days, say on 16th Nov. So, since he made the payment and his subscription got activated on 16th Nov, his monthly billing cycle will be set as from 16th Nov to 16th Dec in spite of the invoice being generated on 10th Nov.
Hence, from the above cases, we can clearly understand that the billing cycle is set according to the first successful payment and subscription activation date.