use warnings;
use strict;
use Data::Dump;
use Mojo::DOM;

my $html = <<'END_HTML';
<span class="remaining-data">54MB used</span>
<span class="expires-data-right-align">1.44GB remaining</span>
END_HTML

my $dom = Mojo::DOM->new($html);
for my $e ($dom->find('span[class="remaining-data"]')->each) {
	dd $e->text;
	my ($val,$unit) = $e->text =~ /([+-]?(?:\d*\.)?\d+)(MB|GB) used/
		or die "Couldn't parse '".$e->text."'";
	dd $val, $unit;
}

__END__

"54MB used"
(54, "MB")