@Badr HOUSSNI
Thank you for the post!
Based off our Azure Key Vault pricing documentation, you're only charged for each successfully authenticated REST API operation, for more info. As for securing your AKV by configuring firewalls and virtual network rules, it doesn't look like that's on our pricing documentation so you shouldn't be charged for that specific feature. However, from my understanding, even with that feature enabled, you'll just be charged per operation as stated in our pricing documentation.
If you'd like more accurate pricing/billing information, I'd recommend chatting with our sales team regarding this issue.
If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.
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