I'm guessing this would be best answered by a mod (Ipstenu? :D). I am considering writing a plugin that will have a bunch of features for free. I then want to try up-sell a couple extra cool features to 'power' users who want a bit more functionality (classic freemium model).
The way I was planning on doing this was to write in ALL the features into the plugin, but require a serial key to be entered to unlock the extra features. Some quick research into the plugin repository rules (http://wordpress.org/extend/plugins/about/guidelines/), specifically point 6, seems to prohibit this.
So I guess my question is, how are plugin devs meant to up-sell to their users? It would seem I would need to write the features into a completely separate plugin. But this brings in headaches like maintaining 2 separate codebases and figuring out a way to push updates to users.
Is that just the way it is, or is there a better solution?