Trace links between requirements and code are beneficial for many software engineering tasks such as maintenance, program comprehension, and re-engineering. If trace links are created and used continuously during a project, they need to have high precision and recall to be useful. However, manual trace link creation is cumbersome and existing automatic trace link creation methods are typically only applied retrospectively and to structured requirements. Therefore, they focus on recall and accept manual effort to cope with low precision. Such manual effort is not acceptable continuously. Furthermore, the maintenance of existing links along with changing artefacts in a project is neglected in most automatic trace link creation approaches. Therefore, we developed and evaluated an interaction log-based trace link creation approach IL to continuously provide correct trace links during a project. IL links unstructured requirements specified in an issue tracker and source code managed in a version control system. In the latest version, ILCom, our approach uses the interactions of developers with files in an integrated development environment and issue identifiers provided in commit messages to create trace links continuously after each commit. In this paper, we present ILCom, its most recent evaluation study, and a systematic literature review (SLR) about trace link maintenance (TM). We also present a TM process for ILCom based on two approaches from our SLR. In the evaluation study, we show that precision of ILCom created links is above 90% and recall almost at 80%. In the SLR, we discuss 16 approaches. Our approach is the first trace link creation approach with very good precision and recall and integrated trace maintenance.