Commitment protocols are modularized specifications of interactions understood in terms of commitments. Purchase is a classic example of a protocol. Although a typical protocol would capture the essence of the interactions desired, in practice, it should be adapted depending on the circumstances or context and the agents' preferences based on that context. For example, when applying purchase in different contexts, it may help to allow sending reminders for payments or returning goods to obtain a refund. We contextualize a protocol by adapting it via different transformations.Our contributions are the following: (1) a protocol is transformed by composing its specification with a transformer specification; (2) contextualization is characterized operationally by relating the original and transformed protocols; and (3) contextualization is related to protocol compliance.