This white paper, titled 'End of Life Manifesto: Best Practices for Managing EOL Open Source Software,' serves as a comprehensive guide for organizations on how to manage open source software that has reached its end-of-life (EOL). It outlines the critical importance of managing EOL software due to the lack of updates and security patches, which can lead to vulnerabilities and compliance risks. The document details best practices for managing EOL OSS, including inventory management, risk assessment, and transition planning. It emphasizes the need for transparent communication with stakeholders and exploring extended support options. Additionally, HeroDevs' approach to EOL management through its Never-Ending Support (NES) product line is presented as a solution for maintaining security and compliance. The paper concludes with methodologies and real-world examples to illustrate the significance of proactive EOL management, highlighting the potential operational disruptions and compliance issues that can arise from using unsupported software.