During the login process for PDF2XL version 7.0+, it's possible you may encounter the following error, even after attempting the offline activation.
If so, please confirm you have access to the following servers (you don't need to physically access these - they simply need to be allowed in the proxy):
Server ports used by PDF2XL
184.106.60.185:80
184.106.60.185:443
https://cogniview.auth0.com
https://api.segment.io
If you have access to these servers, you should not need an offline activation.