Which one are you looking for? There is a desktop version for $50 per year and a premium version for $35 per year:
http://www.hushmail.com/premium/I assume you're using the free account and just forgot to sign in every three weeks? If so, then you could simply register another free account too.
But it's linked to a iTunes account... I can't really lol. But yes forgot to sign in with the 3 weeks.