Hi,
It's unmanaged clients means they will take update directly from Internet. Make sure you are able to access following Internet website successfully.
liveupdate.symantecliveupdate.com
liveupdate.symantec.com
update.symantec.com
akamai.com, if you are not able to access these sites add them as a trusted site.
After running liveupdate are you getting any error ? if yes please share error/error code.
As per your comment "Our main office have SAN agreement with Symantec and we received the antivirus thought it, does i need to register again this product?" - No, you will not have to register it.
It's confirmed that problem is not happening due to license issue, it's related to clients connectivity.