I'm sorry you're having trouble with your license key. I'm going to assume you've tried copy-pasting your license key to prevent any accidental typos when entering the license.
There are a few things that we should check first:
1. What version of Nisus Writer Express did you purchase?
2. What version are you trying to use/license? (you can check using the menu Nisus Writer Express > About Nisus Writer Express)
License keys for version 3.x start with "NXA-".
License keys for version 2.x start with "NWX-".
What does your license key start with?
Thanks- that license key and application version combination is indeed correct.
I looked up your license key and it seems to be working correctly. I've emailed you privately with some more details/tips. Please let me know how things go.
I was successful in getting the license number accepted. I did so by entered it via the dialogue box that shows the demo has expired and has a register option button. I was getting the "license too long" error when trying to enter the license number using the licenses option under the Nisus Writer Express menu.
Happy to help! I don't think how one gets to the licensing window will have any effect on whether the license is accepted, but I'm glad you have everything working now, however it happened.