Determining if your SQL Server instance is experiencing memory issues within the SQL Server Virtual Address Space (VAS) can be a challenge. One way around it is to use the sys.dm_os_ring_buffers to capture alerts registered there that show when virtual memory (also known as internal memory) is low. This is especially useful in situations where you’re running SQL Server on a shared environment with some other service or application.
For more information, see Using sys.dm_os_ring_buffers To Diagnose Memory Issues in SQL Server.
You may also be interested in installing a metric that shows when physical/external memory is low. See Low physical/external memory.