URGENT My free activation key does not work. Six Days left

I am having problems reactivating my free licence that I have had for a number of years. I received the following when I input the activation key. "The licensing server indicates an internal error (Missing required fields) Please contact the vendor to assist you with the activation. Please assist as I have six days left.  Nothing has changed over this period.

It may be a temporary problem with the server. You could wait a day and retry. 

Another option is to register a second Free License using another email address, and try the activation using the new key.

You could also contact sales@emclient.com and ask them to check your license.

Also, please note that if you are using Windows XP, you will no longer be able to activate your license. 

https://forum.emclient.com/emclient/topics/windows-xp-no-longer-supported-issues-with-connecting-to-…

I’m using windows 10!