zbrush 3.1 serial number or unlock key is available to the public, you can freely download the serial key.
This release was created for you, eager to use zbrush 3.1 full and without limitations. Our intentions are not to harm zbrush software company but to give the possibility to those who can not pay for any piece of software out there. This should be your intention too, as a user, to fully evaluate zbrush 3.1 without restrictions and then decide.
If you are keeping the software and want to use it longer than its trial time, we strongly encourage you purchasing the license key from zbrush official website. Our releases are to prove that we can! Nothing can stop us, we keep fighting for freedom despite all the difficulties we face each day.
Last but not less important is your own contribution to our cause. You should consider to submit your own serial numbers or share other files with the community just as someone else helped you with zbrush 3.1 serial number. Sharing is caring and that is the only way to keep our scene, our community alive.