My friend and I would like to buy a 1 month Realm subscription. We would like to upload one of my singleplayer worlds so we can improve it from what it is now. Once the subscription runs out, will I be able to redownload the world that includes everything we worked on? Or will it just be the old version of the world? If I can redownload the world, how is this done? I am running Minecraft Java Edition on a Windows 10 PC.
Yes you can download your world before the subscription ends.
It is all covered on Mojang's help page, Download Realms World - Java Edition:
- Go to your Realms configuration by pressing the button with a tool symbol.
- From the Realms configuration screen, go to your "World backups."
- Finally, all you have to do is press the "Download Latest" button and follow the instructions on the screen.
The world you download will be saved with your singleplayer worlds.