Jeff didn't really define "last". Although invoice numbers generally fall in some sort of order I wouldn't depend on that, but rather depend on the date. Something like:

Select CustomerNumber, InvoiceDate, OtherStuff ;
From lcCursor a1;
Where a1.InvoiceDate In ;
  (Select Max(b1.InvoiceDate);
  From lcCursor b1 ;
  Where B1.CustomerNumber = A1.CustomerNumber);
Into Cursor C_NewResultSingleInvoice

>select a1.*;
>   from lcCursor a1;
>   where a1.InvNo IN ;
>       ( select Max( b1.Invno );
>            from lcCursor b1 );
>   into cursor C_NewResultSingleInvoice

>>I need to list the last items purchased by customer.

>>SELECT INVNO,;
>>       ....
>>       INVDTE,;
>>       FROM (lcDirectory + 'ARTRAN01') tran1 ;
>>       WHERE currhist = " " ;
>>UNION ALL;
>>.....
>>into cursor lcCursor