Hi Glenn,
I'm not positive but I think that Altera requires a yearly License even for their free software.
I know this is the case with their Vintage Altera MAX+PLUS II software that was replaced by the Quartus software.
The MAX+PLUS II software is still available for user's to download off the Altera website, but it requires an Annual License registration. The license is Free but is mandatory.
I'm assuming this is the same for the Quartus Web edition.
Most likely this is for marketing purposes. Sending out promotions via email to members that register for the free software license.
My best guess.
Regards,
-Gerry