Yes, I believe so. As stated on our webpage: Pay upfront (annual & multi-year subscriptions).
Special licensing arrangements should be discussed with our Sales team, as mentioned on the same webpage.
R&D cannot provide information regarding potential special contracts with our Sales team.
The customer always pays per terabyte (if you use 5 GB, you still pay for the entire terabyte).
At the same time, as far as I know, if you purchase Vault through Azure Marketplace, there is an option to receive monthly invoices.
In any case, it’s best to reach out to your sales representative for clarification on these questions, since the team behind this forum is related to R&D rather than sales.