type
  TDetail = record
    A:String;
    B:String;
  end; 
  TMyData = record
    Kode:String;
    Nama:String;
    Harga:Currency;
    Detail:Array [1..12] of TDetail 
  end;
var MyData : Array of TMyData;
procedure satu;
begin
   SetLength(MyData,700000);
   .......
   .......
   .......
end;

procedure dua;
begin
  SetLength(MyData,0);
  Application.Minimize;
  Sleep(5000);
  Application.Restore;
end;

type
  TDetail = record
    A:String;
    B:String;
  end;
  TMyData = record
    Kode:String;
    Nama:String;
    Harga:Currency;
    Detail:Array  of TDetail
  end;
var MyData : Array of TMyData;
var
  Form1             : TForm1;
implementation
{$R *.dfm}
procedure satu;
begin
   SetLength(MyData,700000); // alokasi 
   SetLength(MyData,0); //de-allokasi
end;
initialization
  satu;

  SetLength(MyData, 700000); // get mem
  ...
  MyData:= nil; // free mem
  ...
  SetLength(MyData, SomeSize); // get mem, re-use
  ...
  MyData:= nil; // free mem

kesimpulan: ... di statement SetLength(MyData,0) , string-string yg ada semuanya juga langsung di-freed tanpa menunggu aplikasi terminate.