Does the license expire?
The license always works with the version you purchased.
Beyond Sync Professional based on subscription model. As long as you keep it valid, you can get every single update for FREE, without paying upgrade fee. However, you can only use the version you purchased if the subscription is cancelled.
Beyond Sync Enterprise and Ultimate have an optional Maintenance Agreement to allow you get similar benefits. All new updates are free to you if you purchased MA and keep it valid. Otherwise, you can only use the version you purchased.