Software Expire

I have a program that outputs  a file on the number days left before software license expired. It reads in a text file named expiredt.txt.

expiredt.txt contents are as follows:

EM software          30NOV2015     11/30/2015
ABM software        30NOV2015     11/30/2015
ABM software        30OCY2015      10/30/2015
Publish software    29JUN2016      06/29/2015

I am getting error messages. I am new to writing shell script programs.

here are errors I am getting:

expr: 0402-050 syntax error.
line 22 [: -lt: unary operator expected
line 25 [: -le: unary operator expected
date:Not recognized flag: d
usage: date [-u] [+ "Field Descriptor"]

#!/bin/bash

# Set expiry file date name to first parameter, default to foo5.txt
EXP_FILE=${1:-expiredt.txt}

# Temp file to take the expired products, if any
OUT_FILE=/opt/SM/expired_license/EXP/license/chkexpire.$$

# Get the current date in seconds since the epoch
now_date=$(date "+%s")

while read exp_line; do
  # Get the expiry date as the last field in the expiry file
  exp_date=$(echo $exp_line | awk '{print $NF}')

  # Convert that date to seconds since the epoch
  exp_seconds=$(date -d ${exp_date} "+%s")
  
  # Work out days to go
  days_to_go=$(expr \( 86399 + $exp_seconds - $now_date \) / 86400)

  if [ $days_to_go -lt 0 ]; then
    ((days_to_go=0 - days_to_go))
    echo PROBLEM: $exp_line expired $days_to_go days ago
  elif [ $days_to_go -le 30 ]; then
    echo $exp_line has $days_to_go days left
  fi
  
done < ${EXP_FILE} > ${OUT_FILE}

if [ -s ${OUT_FILE} ]; then
  # One or more products expiring - report them
  echo "$(cat ${OUT_FILE} | wc -l) Product(s) Expiring"
  cat ${OUT_FILE} | mail -s "$(cat ${OUT_FILE} | wc -l) Product(s) Expiring" j.mj@aol.com
else
  echo File ${OUT_FILE} is empty, so no expired software
fi

rm -f ${OUT_FILE}

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