When you receive a new message on Facebook Messenger, you'll have 24 hours time period to send your reply. Otherwise, you may receive (#10) This message is sent outside of the allowed window error message.
Moreover, we're currently in contact with Facebook team to get the privilege because we believe that Juphy customers must have the ability to reply after 24 hours window because the main focus of the tool is customer support. Some support cases may need more than 24 hours to be solved. Please follow the https://juphy.canny.io/feature-requests/p/facebook-24-hour-time-limit for further updates.