You join Qatar Airways Privilege Club where you can earn and spend Avios, which is their currency equivalent to KrisFlyer Miles.
You can do a dummy booking to determine seat release and it looks closer to a full year. At the moment I can see up to 9th July 2024. This is for general release and there is no guarantee that award seats will be released. Often you will find on popular routes and/or at peak times that no award seats will be released as QR realises they can be sold for cash which is much more preferable to them.
Avios do expire after three years, but any earning or spending re-starts the three year clock.
https://www.qatarairways.com/en/Priv...lessAvios.html