Hello
I got free licence for your application but I can’t activate client 
facing the same problem… i just have 2 accounts but key not working
Same here. Have written support.
It seems there is a problem with recently issued license keys. So far there has been no official response from eM Client staff.
You are not alone. Please see https://forum.emclient.com/emclient/topics/can-not-activate-the-free-version
Hello Everyone,
the temporary bug on our license server which happened last night causing the problem with saving new licenses has been resolved.
You can now create Free licenses on our website again - https://www.emclient.com/free-license
For any Pro license users seeing this who experienced this issue - please get in touch with our Pro support immediately and we will re-create your purchased licenses.
We are very sorry for the inconvenience.
Best regards,
Olivia