What is the least annoying but still fair way to limit a plugin demo?

Is 14 days of full functionality the right way to go?
What about the limitations after the trial ends, should some functionality remain?

Here are some limitations I can think of:

1. Short pauses in audio (with or without a warning message).
2. Short noise bursts in audio.
3. Plugin state not saved with the DAW project.
4. Disabled presets.
5. A huge DEMO label somewhere on the plugin.
6. Completely disabled plugin after trial ends.