Thank you! We’ll investigate and see if the link is wrong. It can also be your system that is configured to not open links in a working browser. What we do when you click a button like that, is we launch the system-registered default handler for http URLs. If none is configured, or wrongly configured, it won’t work.
In the meantime, the link you want is: https://account.axcrypt.net/Home/Purchase .
Thank you for reporting this. We’ve identified the problem, and it will be corrected in the upcoming release. If you email support, we’d be happy to give you 6 months complimentary service as a bug-bounty!