Current License -> "Upgrades Expire On" What is mean?

The "Upgrades Expire On" represents the last day of the current funded license period. With Perpetual licenses such as the floating licenses on the server shown in the image, the server will continue to be active and usable beyond the end of the current funded license period. However, support and upgrades for servers using this license type will end on the "Upgrades Expire On" date, unless those licesnse are renewed. Renewal costs for on-going support and upgrades is at a much reduced cost from that of the original license purchase, provided the maintenance period isn't allowed to lapse before renewing that license.