When you bought Yowindow on-line you received an email from Plimus Sales...
In this mail there's a link to click in case you need support for your product...
You can also mail
support@repkasoft.com
You also must have received a confirmation mail from
sales@repkasoft.com when you purchased
the software. That mail included your registration code...
Perhaps it is still present in your inbox or on the mailserver...
Hope this helps...
Wally©...
(Ignorance can easily be overcome...Stupidity is 4ever...)