The regular expression you have entered will match anything.

$text = 'I like donkeys';
if ($text =~ /a*((ab)*|b*)/) {    print "Success ($1)\n";  }
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What you've written there is:

 $text =~ / a*    # zero or more of 'a'
                  (     # followed by
                 (ab)*  # zero or more of 'ab'
                  |     # or
                  b*    # zero or more of 'b'
                 )/x
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So please, less of this 'perl is dead'. Go and read through perlre.