Paul, the answer’s simple: even if AxCrypt shut down you can still use the software without needing a verification code.
Svante has previously stated that you do not need to use a real email address.
“The first time you start AxCrypt a real email address is required. Click help for more information” – If you’re off line when starting the first time, the only requirement is an email address that looks real, i.e. has the correct form. There’s no requirement to be online at any time to use AxCrypt.
Obviously you should a copy of the latest AxCrypt version backed up in the cloud somewhere for additional assurance although there are plenty of copies floating about on the internet.