There are a number of things you ought to tidy up in your code. First off, always use strictures (use strict; use warnings;).

Use the three parameter version of open.

Avoid slurping files (@file=<FILE>;).

Use a precompiled regex instead of interpolating a string into a regex.

Early exits and statement modifiers work very well to eliminate excessive indentation (see next unless $_ =~ $find; below).

Multiple ! marks are a sure sign of a demented mind (although that may not be a programming tip). :-)

Consider the following reworked example:

use strict;
use warnings;

my $license = 'Wibble';

open FILE, '<', $license || die ("Could not open the file\n");

my $find = qr'license @abc';

while (<FILE>) {
    next unless $_ =~ $find;

    print "Found!\n";
    print "$_\n";
}
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