try this header available you to download with resume 
i suggest use database or log file for understand  the file downloaded or not because this header available downloader to download part-part     
get Request range from downloader you can use fseek to read range of file
$Range=@$_SERVER['HTTP_RANGE'];//Range: bytes=843530240-
$Cach="";
if($Range!=""){
  $Range=explode("=",$Range);
  $Cach=(int)trim($Range[1]," -");      
}
caching controller 
function caching_include($file) {
     $headers = $_SERVER;
     // Get the modification timestamp
     if(!(list(,,,,,,,,,$lastModified) = @stat($file))){
           echo Error;
           exit();          
     }
     // Build our entity tag
     $eTag = "ci-".dechex(crc32($file.$lastModified));
     if (false and (strpos(@$headers['If-None-Match'], "$eTag")) &&(gmstrftime("%a, %d %b %Y %T %Z", $lastModified) == @$headers['If-Modified-Since'])) {
        // They already have an up to date copy so tell them
        header('HTTP/1.1 304 Not Modified');
        header('Cache-Control: private');
        header("Pragma: ");
        header('Expires: ');
        header('Content-Type: ');
        header('ETag: "'.$eTag.'"');
        exit;
     } else {
       // We have to send them the whole page
        header('Cache-Control: private');
        header('Pragma: ');
        header('Expires: ');
        header('Last-Modified: '.gmstrftime("%a, %d %b %Y %T %Z",$lastModified));
        header('ETag: "'.$eTag.'"');
     }
  }
header for download
header("Server: SepidarSoft/ir-system");//server name 
header("Date: ".date("a,d b Y H:M:S GMT",time()));
header("X-Powered-By: SepidarSoft");
header("Cache-Control: public");
header("Content-disposition:filename=\"".$BaseName."\"");//file name
caching_include($FPatch);//caching controller 
header("Accept-Ranges:bytes");
header("Content-Transfer-Encoding: binary\n"); 
header("Connection: Keep-Alive");
header("Content-Type: $Type");//file type like application/zip
header("Content-Length: ".($FSize-$Cach)); //length of download it is for resume  
header("Content-Range: bytes ".$Cach."-".($FSize-1)."/".$FSize); //download range it is for resume
header("HTTP/1.1 206 Partial Content",true);
set_time_limit(0);
if use set_time_limit(0); in code if user connection become disconnect php continue until finish work for that your file will be remove you download or not after one request you can use connection_status()==0 for check connection  like below
$Speed=102400;
fseek($Handle,$From);//if use resume it is useful 
while(!@feof($Handle) and (connection_status()==0)){
    print(fread($Handle,$Speed));
    flush(); 
            ob_flush(); 
 } 
 if(connection_status()==0){//with this condition you can understand download is down by user 
       unlink($this->dirPath."/".$archive_file_name);
 }