Charge for Used Units on Cancellation (Usage-Based Subscriptions)

Currently, when a customer cancels a usage-based subscription, we do not charge them, even if they have already consumed some units.

Requested Enhancement:
Enable charging customers for the units they have already used when they cancel a usage-based subscription.

Expected Behavior:

• Track consumed units up to the cancellation time
• Generate a final charge/invoice for the used units
• Then cancel the subscription successfully