Commitments are financial agreements between you and your publishers, customers, or/and your customers' agencies that are often are made on a yearly basis (yearly agreements) which you can track in ADvendio. They can also store agreements you made with your agencies about agency commission/earnings or third party commissions for your intermediaries.
Commitments are typically agreed to at the beginning of the year or even earlier at the end of the preceding year, alternatively you can also have quarterly or monthly agreements. It manages the planned advertising spendings/turnover in order to achieve a certain discount or rebate in kind (value add offers).
I.e. You can set up scaled discounts related to the amount a publisher/agency spend in that year. Throughout the year ADvendio calculates the actual revenue figures for you. So this can be matched with the earlier commitment value to verify that numbers are reached and the "real" discounts need to be applied.