After some search on the Internet, I've found that the application has been discontinued.
"Grammar Expert Plus has been discontinued and is no longer being updated." - Wintertree Software
Technically, at this point you are allowed to share the application, but the rules still apply. You can't make any profit from it.
However, this is just my opinion , but the ones who can offer additional help are the developers.
Use the contact form and ask them the same question: http://www.wintertree-software.com/contact.html