Pelles C is freeware for any use: personal, commercial, etc. No registration is required to download it, and you can use it anonymously.
Pelles C can be freely distributed, but it can not be sold.
Pelles C is provided 'as-is', without any expressed or implied warranty. In no event will the author be held liable for any damages arising from the use of this software.

Pelles C is totally free.