Pro Activation Key vs. License

What is the difference between License and Activation Key? I have an activation key for the Pro version as of last August, but I am not able to download and update my eM Client that just went to version 6.

Hi, License can be pro or paid, it is something that give you right under some circumstances to use products/services.

activation key is for eM client to tell what license do you have and to connect it with our licensing system.

To your issue, do you use free or pro license?