On the journey of learning a language we are exposed to countless words that are easily forgotten and subsequently difficult to find again. This study investigates how to design a personal data management system that enables its users to efficiently organize, find and input the words and phrases that they encounter on their journey. Using DSRM, an artifact was iteratively developed and tested in usability tests and interviews by a total of 10 participants. The feedback from the respondents indicates a strong demand for this type of app and also uncovered design knowledge in this new context. The contribution of this study is a set of 14 design principles for making data management in language learning apps more user-friendly and efficient.