The beta is a test software in the first place. The main purpose of the beta is to let users test this new version on their computers to help us identify any incompatibilities and release the final version sooner.
Regarding the limitations, both v4.2 and v4.3 beta have the same limitations in Demo edition. In particular, the Demo always filters only a part of the image (1024x1024 pixels). You can find the detailed description of Demo vs Home vs Pro plug-in capabilities in the
featuremap.
If you want to test Neat Image to see if its filtration is good enough for your pictures, you can do that using the Demo edition in the following way:
1. in Photoshop, select any part of the image where you want to apply noise reduction;
2. invoke Neat Image Demo plug-in, adjust it using this
howto and apply;
3. repeat steps 1 and 2 on other areas of interest and/or other images.
If you decide that the noise reduction by Neat Image is good enough then please consider ordering a license for either Home or Pro plug-in /Mac. They don't have size limitations and you can directly process your images.
Hope this helps.
Vlad