We don’t support this in the app, but it can be done manually (and it’s only required once per Premium period).
1) Sign up, sign in, purchase etc on an Internet-connected PC. Copy the AxCrypt installer and %localappdata%\AxCrypt\UserAccounts.txt and UserPublicKeys.txt to a medium you can access in the disconnected PC.
2) Install and start AxCrypt on the disconnected computer. You will be able to sign up etc, but offline. Do this, ensure you use the exact same email. Enable the “Always Offline” option. EXIT AxCrypt.
3) Copy “UserAccounts.txt” and “UserPublicKeys.txt” to %localappdata%\AxCrypt on the disconnect PC.
4) Start AxCrypt again. You should now be in always offline Premium mode.
In the future you’ll be able to download a license file containing this information directly from the web or from the app, and import it directly to the app.