VB

Journaling has been included with NX from around NX3 (if my memory serves). Basically, if you have a license that allows you to create a model, you can use journaling. Journaling gives you access to the NXOpen API, some of these commands will allow you to interact with the user, such as picking points, planes, vectors, etc (see the specify Csys section of http://nxjournaling.com/content/wrangling-wcs). If you are running on the Windows OS, you will also have access to many standard Windows dialog boxes such as the folder picker, message box, input box, etc. See:
http://nxjournaling.com/content/using-message-boxes
http://nxjournaling.com/content/user-input-input-boxes
http://nxjournaling.com/content/user-input-folder-picker

Also, with the help of an integrated development environment (IDE) such as VB.net express, you can create and use your own custom dialog boxes (WinForms). See:
http://nxjournaling.com/content/using-winforms-journals

There is a lot that you can do with just journaling; all of the articles on this site only use the journaling capabilities that are available to practically every NX user. However, journaling does have its limitations.

If you want to create custom dialog boxes with the NX "look and feel", then you will want to get a "UI styler" license. Also, an "author" license (there are several types, depending on your development language of choice) will allow you to compile your code, share it in compiled form, and do a few other things not allowed with plain journaling alone.

So, in direct response to your question: "do I need a license to create vb.net apps and forms?"
The answer is: no; but there are other licenses available to give you more capability.