Can-t-authenticate-WL-6-9-The-request-failed-with-an-empty-response

Hello,
I bought a one year license for WLD at the end of last summer. It's been running fine until a few days ago... now, when I launching WLD I see a few error messages:
"you must log in within the next 1 days to continue to use WLD 6.9. Do you want to log in now..."
Authenticate with a key fails and "error: the request failed with an empty response" is shown
"Log in failure: the request failed with an empty response" shows.
But then WLD seems to work okay after these error messages are closed.
Can I continue to use 6.9 or do I need to upgrade to 7 to continue using the program?
Thanks