+=item C<is_last_billing_date_in_order_value_cycle %params>
+
+Determines whether or not the mandatory parameter C<date>, an instance
+of L<DateTime>, is the last billing date within the cycle given by the
+order value periodicity. Returns a truish value if this is the case
+and a falsish value otherwise.
+
+This check is always true if the billing periodicity is longer than or
+equal to the order value periodicity. For example, if you have an
+order whose value is given for three months and you bill every six
+months and you have twice the order value on each invoice, meaning
+each invoice is itself the last invoice for not only one but two order
+value cycles.
+
+Otherwise (if the order value periodicity is longer than the billing
+periodicity) this function iterates over all eligible dates starting
+with C<first_billing_date> (or C<start_date> if C<first_billing_date>
+is unset) and adding the order value length with each step. If the
+date given by the C<date> parameter plus the billing period length
+equals one of those dates then the given date is indeed the date of
+the last invoice in that particular order value cycle.
+