This thesis is about current cloud systems and the billing methods featured within them. It details the technology behind these systems, illustrates widespread models, and demonstrates the needs of users and ways of future improvements for cloud systems. The thesis furthermore describes the most common cloud system – OpenStack – and software solutions supported through its open interfaces, and gives an overview of open source billing solutions for OpenStack systems developed by the community. Lastly the thesis elaborates on the OpenStack based cloud system of the Hungarian Academy of Sciences Wigner Research Centre for Physics Data Center, its groups of users and similar systems in the industry. Give a show from the realized system and its important creating elements, the database structure used by the system, furthermore from the automatized environment installing and using this system and the future potentials of its development, summarizing all the work that has been done and future prospects.