LifelongAgentBench is designed to simulate real-world continuous learning environments, enabling developers to test AI agents across a sequence of evolving tasks. The framework offers a plug-and-play API to define new scenarios, load datasets, and configure memory management policies. Built-in evaluation modules compute metrics like forward transfer, backward transfer, forgetting rate, and cumulative performance. Users can deploy baseline implementations or integrate proprietary agents, facilitating direct comparison under identical settings. Results are exported as standardized reports, featuring interactive plots and tables. The modular architecture supports extensions with custom dataloaders, metrics, and visualization plugins, ensuring researchers and engineers can adapt the platform to varied application domains.