If the intention is for a yearly payment to be made upfront for a 12 month subscription fee together with a set number of dimension units for full year, how should it be metered?
Does it mean that we have to calculate the and maintain the delta using the Metering API to get our desired numbers and then apply a negative delta to get back to a 0 for example to make sure we didn’t bill for the next month and so on?
No, only units sent to the Metering API will be charged to the End-Customer - i.e. the Metering API does not do any recurring charges. There is no need to adjust the units. If the SaaS sends all the units in the first month, the client will be charged for those units that month and only that month, even if it is for the entire years subscription and dimension units.