Buy once instead of Boxcryptor
2 apps in the directory cover what people use Boxcryptor for. All of them cost nothing at all.
Read the catch on each one before you switch — a one-time price is not automatically the better deal, and we say so where it is not.
The replacements
Cryptomator
client-side encryption for files you keep in someone else's cloud
Free Open source
Free on the desktop only — the iOS app is a separate €29.99 purchase
VeraCrypt
encrypted volumes that open on macOS, Windows and Linux alike
Free Open source
Needs macFUSE, a system extension that can lag weeks behind a new macOS release