Magiczoom can be installed on a TRIAL basis to start with. The TRIAL version appends an alert to your zoomed images, and to get rid of that message you purchase a licence and receive a different JS file, which you then overwrite the original JS file(s) with.

Magiczoom has an AUTO-INSTALLER, but I don't recommend you use this auto installer because it can create some conflicts. It is better to follow their MANUAL INSTALL instructions.