What is "Expire date", and how can it be used?

"Expire date" means that the credential/certificate/document is only valid until this specific future date. When the date comes, you can choose what you wish should happen with the document. For example, text could appear that highlights that it is expired, or an email can be sent to notify the Recipient. Let us know what you wish should happen, we have several settings for this. 

Expiration date can be used for many reasons, for example if a certification needs to be renewed ever 2 years..