In the future, James, be aware that activation issues are always free. Call or email our sales department and they'll help you through it.
In the left side, go to License Keys.
Click on your license.
If you don't have activations remaining, you'll see a button that says "Reset Activations" in the second section. Click that and follow the prompts.
FYI, I'll let the dev teams know that the error message should be made more clear.