Some products are licensed with the CS: 12 hour Continuous Concurrent license type. When this type of license is requested, it is set to expire after a 12 hour period, but can be returned and requested multiple times in those 12 hours. However, once the license expires, it enters a 12-hour expiration period. At the end of that 12 hours, the license is renewed and once again available to be requested.
The 12 hour expiration periods are represented by expiry sessions in the Licensing Portal analytics. Instead of these sessions having a request and return time, they only have an expired and renewed time. All the sessions that used this license before its expiry period will have the same expired and renewed time as the expiry session.