Per ASU 2014-09, a performance obligation is a promise in a contract with a customer to transfer a good or service to the customer. If an entity promises in a contract to transfer more than one good or service to the customer, the entity should account for each promised good or service as a performance obligation only if it is (1) distinct or (2) a series of distinct goods or services that are substantially the same and have the same pattern of transfer.

RevRec Ready Hot-Tip #17 - What is a Performance Obligation?