Memory leaks are common issues that can affect the performance of your Node.js applications over time. Here's how you can fix memory leaks in your Node.js application:

1. Identify the source of memory leak: To identify the source of a memory leak, start by analyzing your code and identifying any patterns or trends that may suggest memory usage is growing uncontrollably. You can use various tools like heapdump, pm2, and node-inspector to monitor memory usage over time.

2. Remove unused references: Once you've identified the source of the memory leak, start removing any references to objects that are no longer needed. This will prevent these objects from being garbage collected and freeing up memory.

3. Use memory profiling tools: You can use memory profiling tools like Chrome DevTools or Node.js built-in --heapdump option to monitor memory usage over time. This will help you identify any patterns or trends that may suggest memory leaks are happening.

4. Avoid global variables: Global variables can cause memory leaks because they retain references to objects, even after the object has been deleted. To avoid this, use local variables instead of global variables whenever possible.

5. Use built-in garbage collection: Node.js provides a built-in garbage collector that automatically frees up memory for objects that are no longer needed. Be sure to use this feature correctly and only when necessary.

6. Update libraries: Keep your libraries updated with the latest versions to ensure they have bug fixes and performance improvements. This can help prevent memory leaks caused by outdated or buggy code.

7. Use asynchronous programming: Asynchronous programming can help prevent memory leaks caused by event loops that are not properly managed. Be sure to use callbacks, promises, and async/await appropriately to manage your event loops effectively.