Howdy :)

This is quite simple. Because your data is regular, you can use split to extract the date/time stamp from each record. Then you can use something like Date::Parse to convert the date/time stamp into a unix timestamp. After that, it's just a bit of simple arithmetic.

Here is some example code to demonstrate:

#!/usr/bin/perl -l
use strict;
use warnings;
use Date::Parse;

my $cutoff_date = time - (45 * 86400);

while (my $line = <DATA>) {
    chomp($line);
    my $date = (split /\|/, $line)[15];
    my $unixdate = str2time($date) or next;
    print "I would ", $unixdate < $cutoff_date ? "archive" : "not arch
+ive", " $date";
}

__DATA__
type|address|city|state|size|rent|term|company|contact|phone|email|web
+site|ID|REMOTE_ADDR|HTTP_USER_AGENT|DATE|SORTORDER
MFG|10 Oakmead Pkwy|San Jose|CA |10,000|$1.25|Net|Cushman Wakefield|To
+m Cushman|408 555-8777|tom@cushman.com|http://www.google.com|1000000|
+76.102.98.35|Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET 
+CLR 2.0.50727)|16:01:08 2007-01-10|1003
LAND|10 Oak|San Jose|CA|14,000|$1.25|Net|Ritchie Commercial|Don Ritchi
+e|408 555-8777|tom@cushman.com|http://www.yahoo.com|1000001|76.102.98
+.35|Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.5
+0727)|16:28:03 2008-01-10|1002
[download]

Which prints:

I would archive 16:01:08 2007-01-10
I would not archive 16:28:03 2008-01-10
[download]

Hope this helps,
Darren :)