Is Realm Works what I need?
 

So, I'm searching for a non subscription program to manage my Roleplaying Game Campaigns.

This alone ... yes ... Realm Works would work wonderfully, I assume ...

My problem is: I also need a program, that players can access and write things down for them. Such as the background story of their respective character ... or the log of the played sessions ... is that possible with realm works? Do I need a subscription for this?

Thanks!

No. In Realm Works, the GM can edit things but Players can only view things.

If the group uses Hero Lab (either one) for their characters, they can add Journal entries and other things to there. It won't show up as part of your world reference material, though.

Also, Realm Works is no longer being developed and hasn't been in development for several years. At least as far as I know.

It is good at what it does, but new features aren't likely.

The developer likes the software, but I suspect it wasn't generating enough revenue. It will likely be supported forever, but in its current state.

I liked it when I used it, but haven't used it in quite a while.