my $string = "ERROR blah license will expire";
if ($string =~ /^ERROR\b.+?(?:Error processing Cancel Execution|license will expire)\b/m) {
    print "NOT MATCHED\n";
}
else {
    print "MATCHED\n";
}

##</code><code>##

if ($string =~ /^ERROR\b/m and $string !~ /\b(?:Error processing Cancel Execution|license will expire)\b/) {
    print "MATCHED\n";
}
else {
    print "NOT MATCHED\n";
}