4.10.5 was released early in 2006...if that's when you bought Pro, your Pro benefits are way out of date. So your email address won't be recognised because it won't be in the database any more.

Back then, a Pro payment entitled the user to 6 months worth of free updates & support (there's now a 12 month deal as well).

If you want a new version of Pro, you'll have to buy again.