Quality is delighting customers
Manual testing can't find Memory leaks ..!
go through this site.
Other thing you could is -
1. Open the Task Manager and Select the services (related to your application) running under 'Process' tab
2. Monitor the Memory Usage while performing some operations and during Idle time. Increase in the memory usage while performing some operation is accepted but verify the memory usage is not increasing continuously in steps of 2k, 4k, 8k...