Licence problem: "not valid key"

I have a licence for 2 devices. I use the licence for 1 laptop computer and 1 desktop computer (my office).

I received a new laptop for christmas. I deactivated my licence on the old laptop and I activated emclient on my new laptop. This was ok.

Today I’m back at my office, but on my desktop computer emclient showed me that my licence is not valid.

How can I fix this?

Contact sales@emclient.com