How can we know about the used quotas from the API?

Hello, We want to move our Free plan to Pro plan, could you help me where can we get the used quota infomration?

Access to quotas and alerts is a PRO feature.

Currently we send out emails when 50%, 70%, 90% and 100% of the limit is reached.

Please note that we do not charge for extra conversions automatically. Instead, if you reach the limit, we will contact you and you can decide if you want to pay for additional conversions or stop for the current billing period.