Lines 50 and 51 are:

                $metrics{$product}{$date} = $day;
                $metrics{$product}{$date}{$hour}{$user} = $val;
[download]

So, on line 50 you set $metrics{$product}{$date} to be a scalar and then on line 51 you try to treat it as a hash ref. That's incompatible.

Following #2 in Basic debugging checklist, I would recommend printing out the hash after every time you assign to a key or subkey of your %metrics hash. Because it's a complex structure, use Data::Dumper, as:

use Data::Dumper;
...
# after some assignment like
    $metrics{$product}{$date} = $day;
    print STDERR Dumper \%metrics;
    $metrics{$product}{$date}{$hour}{$user} = $val;
    print STDERR Dumper \%metrics;
[download]

as a one liner, with hardcoded values, for the first assignment and print:

C:\usr\local\share\PassThru\perl>perl -MData::Dumper -le "$metrics{pro
+duct}{today} = 'Wed'; print STDERR Dumper \%metrics"
$VAR1 = {
          'product' => {
                         'today' => 'Wed'
                       }
        };
[download]

You might then notice that at the first print, the value of the 'today' key is a string, 'Wed', and not another { nested => hash }. With a string as the value of {today}, you cannot take another subkey (like {today}{12}), because strings don't have subkeys. I think you need to rethink your data structure. Maybe show us in the Data::Dumper-like notation printed above, what you do want your data to look like when you're done, and we can help you organize your data into that format.

If you want to build the hash

Then $metrics{$product}{$date} has to be a hash reference. It can't be used the store the day. If you need to store the day use a separate hash

 $calendar{$date} = $day;
[download]

Pretty printing is left as an exercise:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %lic_info;
my $pending_product="";
my $pending_user_count=0;

my %actions=(
   "Flexible License Manager" => sub{ 
         @lic_info{qw|DAY DATE TIME|} = $_[0]=~/ on (\w+) (\S+) (\S+)$
+/;
       },
    "Users of " => sub{
        my ($product,$issued, $usecount) = $_[0]=~/Users of (\w+):  \(
+Total of (\d+) license\w? issued;  Total of (\d+) lic/;
        $lic_info{$product}{ISSUED}= $issued;
        $pending_user_count = $lic_info{$product}{USED}= $usecount;
        $pending_product    = $product;
    },
);

my $regex = "(" . join ("|", keys %actions) . ")";


while (<DATA>){
   if ( m/$regex/ ){
      $actions{$1}->($_); # Where the work happens 
   }elsif ($pending_product){
      next if m/^\s+$/;
      next if m/floating license/;
      next if m/\s*\S?$pending_product/;
      push @{$lic_info{$pending_product}{USERS}},
         m/(\S+)/;
      --$pending_user_count or $pending_product = "";
   }
}

print Dumper \%lic_info;

__DATA__
lmutil - Copyright (c) 1989-2009 Flexera Software, Inc. All Rights Res
+erved.
Flexible License Manager status on Wed 1/2/2019 07:00

[Detecting lmgrd processes...]
License server status: 27000@unodecx80
    License file(s) on unodecx80: E:\Program Files (x86)\IBM\RationalR
+LKS\common\rational_server_perm.dat:E:\Program Files (x86)\IBM\Ration
+alRLKS\common\rational_server_temp.dat:

 unodecx80: license server UP (MASTER) v11.10

Vendor daemon status (on unodecx80):

   ibmratl: UP v11.10
Feature usage info:


Users of ClearCase:  (Total of 10 licenses issued;  Total of 1 license
+ in use)

  "ClearCase" v1.00000, vendor: rational
  floating license

    amlove unodecx86 WI_zfTVVG-n7Ph2jhkOo #u#amlove#u# (v1.0) (unodecx
+80/27000 615), start Wed 1/2 6:56 (linger: 1800)

Users of ADALangPack:  (Total of 1 license issued;  Total of 0 license
+s in use)
[download]

$VAR1 = {
          'ClearCase' => {
                           'USED' => '1',
                           'USERS' => [
                                        'amlove'
                                      ],
                           'ISSUED' => '10'
                         },
          'ADALangPack' => {
                             'ISSUED' => '1',
                             'USED' => '0'
                           },
          'DATE' => '1/2/2019',
          'DAY' => 'Wed',
          'TIME' => '07:00'
        };
[download]

Update: FYI/FWIW - I was a ClearCase admin in a previous job, decades ago, and I sympathize. That was what taught me perl - so good luck !

I am tempted to try some code but I think it will save us all some time if you present your data. Not as a file, but as how you see it being parsed from a file-line to a data structure. In pseudo/abstract-code. Then, along with you, we can see if a hash is a good idea. It seems to me that you thought about how you want your data structure to be but you have some difficulty in doing it in Perl. So talk abstract if you have too.