Application object: Returns the amount of memory that Microsoft Excel is currently using, in bytes. Read-only Long.
PivotCache or PivotField object: Returns the amount of memory currently being used by the object, in bytes. Read-only Long.
Remarks
For PivotCache objects, this property reflects the transient state of the cache at the time that it’s queried.
If the PivotCache object has no PivotTable report attached to it, this property returns 0 (zero).
Example
This example displays a message box showing the number of bytes that Microsoft Excel is currently using.
MsgBox "Microsoft Excel is currently using " & _
Application.MemoryUsed & " bytes"