How do I store data from month to month in Google App Script?

I have an app script that is setup to a trigger to automatically send out the statistics on the 1st of each month. I have tried to use PropertiesService() class to store the data. I currently have them stored in key name pairs. The variables I need to store are as follows

  • Month
  • Total Referrals
  • Intakes Complete
  • Intakes Returned

How can I save the data from the last month (Example: September) when the email is sent out on the first of the month and pull that data to send out the new statistics for October. The goal is to compare the two months together. The data it’s pulling from is constantly changing and the data on October 1st will be different on October 2nd.