A new Enterprise Server license allows for free upgrades to any new major TeamCity version released during the license maintenance period (12 months).

To continue receiving upgrades after that period, you will need to renew your Enterprise Server Upgrade Subscription for $999 per server/year. Subscription renewals commence from the expiration of your previous subscription period, regardless of when the subscription renewal is purchased. Obtaining the new version of TeamCity under an Upgrade Subscription automatically terminates your rights to use any of the previous versions.