SeeYou 4 registration

In April, it was mentioned on this group that:

"To use version 4.x, you need to buy an upgrade - unless you purchased
SeeYou
for PC or an upgrade in the last year. "

I purchased version 3 last winter so i downloaded version 4. I thought
I put in my name and registration key but today when opening SeeYou it
said my trial period had expired. i tried to enter my registration key
and it doesn't work.

I see an upgrade on Naviter's website for $93 US, nothing about
upgrading within a year for free. Is this not true? if so how do i go
back to version 3?