In recent years, the open science and, specifically, the open access to scientific publications and research data have been topics of interest for the international scientific community, including the European Union and its member states. Recently, this interest has been amplified by the development and launch of the Horizon Europe framework program and national research and innovation programs. For our country, the National Strategy for Research, Innovation and Intelligent Specialization 2022-2027, recently adopted, includes the two topics among its specific objectives. In this context, the paper analyzes the results obtained by the Horizon 2020 program in the implementation of the open access policy for publications and research data generated by its own projects, as highlighted in the final program monitoring report. The provisions of the model grant agreement regarding open access and the pilot dedicated to open research data are presented. The typology of monitoring indicators is detailed and the main indicators and their values are listed. Some conclusions drawn from the accumulated experience, with the aim of improving this activity in Horizon Europe, are reviewed. For this program, the focus on impact-based evaluation of its results is also highlighted. This approach is illustrated by short-, medium- and long-term impact monitoring indicators specific to open science.