EMAIL CLIENT STOPED WORKING AND I HAV A A VALID LICENSE

Dear Sirs,I bought four licenses of eMail Client for 4 work units (2 PCs and 2 Lap Tops), but today one of them suddenly stopped working. I do not know what it is happening. The eMail Client is not working and points that my license has expired. However, I am using the same PC that until yesterday eMail Client worked well with no problem. 
My email is otavio2222@uol.com.br
The order I bought the license for this PC is EMC160720-4944-36866 (20.07.2016)
I did not change the HD nor I did anything that could erase the license, as I remember.

Hello Otávio,
I see your four licenses (one with 1 seat, second with 3 seats) but only one of them is activated.
I will sent a reset message from our server to you with your license keys.

The multiple license is completely unused. So, use that key to activate in your current device in Menu>Help>License.

Regards,
Olivia