Anyone who has an active license when XF 2.3 is released will get access to download XF 2.3.
So, for example, if a license is purchased today and XF 2.3 is released within the next 12 months, then you will be able to download XF 2.3 at no extra cost.
If a license is purchased 10 months ago and XF 2.3 is released in more than 2 months (by which time the license will be expired), then the license will need to be renewed in order to access the new versions.
License extensions are currently $55 to renew for an additional 12 months.