While we don't explicitly state in our license, you can use uniGUI beta for commercial use without any restrictions.
You have two options:
1) Purchase the commercial version and continue development using it.
2) Stay with last free beta version and continue development using it.
Which means if you are happy with latest (free) beta version and it meets your requirements you can stay with it and use it in your commercial projects. Your current projects and associated licenses won't expire.
Important note: At a certain point we may stop publishing free betas and switch to betas with commercial licenses. Until we make such a distinction all beta versions are free for commercial use.
Yes.
Only if you want to use features in newer version.
As I told above you can stay with latest beta version which you are happy with.
Please see our new roadmap. Version 0.90.0 will answer lots of such questions.