use warnings;
use strict;

use Data::Dumper;

my %clients;

while (<DATA>) {
    my ($client, $rest) = split /\|/;
    $rest =~ s/\s+//g;
    my @months = split /\d+/, $rest;
    $clients{$client} = \@months;
}

print Dumper \%clients;

__DATA__
IBM | February 1 March 5 July 4
Oracle| January 3 March 4 April 6 May 5
RedHat | March 2 June 3 August 1

##</code><code>##

$VAR1 = {
          'IBM ' => [
                      'February',
                      'March',
                      'July'
                    ],
          'Oracle' => [
                        'January',
                        'March',
                        'April',
                        'May'
                      ],
          'RedHat ' => [
                         'March',
                         'June',
                         'August'
                       ]
        };