A method and an apparatus for determining a usage level of a memory device to notify a running application to perform memory reduction operations selected based on the memory usage level are described. An application calls APIs (Application Programming Interface) integrated with the application codes in the system to perform memory reduction operations. A memory usage level is determined according to a memory usage status received from the kernel of a system. A running application is associated with application priorities ranking multiple running applications statically or dynamically. Selecting memory reduction operations and notifying a running application are based on application priorities. Alternatively, a running application may determine a mode of operation to directly reduce memory usage in response to a notification for reducing memory usage without using API calls to other software.