You need an expression, something that can return a value. If you use something that doesn't return a value (like foreach), how could the elsif decide whether to enter or not? Your foreach doesn't even have a body, which makes even less sense.

elsif ($lec eq $outdate{$key1}) {
   foreach (@pmis) {
      if ($_ eq $outdate{$key1}) {
         ........ 
      }
   }
}
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