What are some alternatives?
When comparing Themida and UPX, you can also consider the following products
VMProtect - VMProtect Ultimate - All-In-One Solution For Software Licensing And Protection.
Alienyze - Alienyze is a software packer and protection solution for windows executable files. Alienyze allows developers to easily protect their software against cracking and reverse engineering.
PELock - Software copy protection against reverse engineering with anti-cracking & anti-debugging techniques. Software license key system with time trial options.
ExEinfo PE - Packer, compressor detector / unpack info / internal exe tools.
Free UPX - Graphical interface for the UPX packer, UPX 3.91w, UPX 3.92w, UPX 3.93w, UPX 3.94w, Ultimate Packer for eXecutables, EXE packer
LockBytes - LockBytes is a Lightweight DRM (Digital Rights Management) solution for licencing Windows executable files.