If you are looking for a free alternative, consider open-source clients like , which do not require a registration code and are actively maintained.
Unlike modern software with online activation servers (or "phone home" features), mIRC 6.35 used an . The program checked the key you entered against a mathematical formula. If it matched the expected pattern, registration was granted. Mirc 6.35 Registration Code
Sharing or requesting registration codes for mIRC (or any software) violates copyright policies and terms of service. mIRC is , meaning you can try it for free for 30 days, but continued use requires a legitimate license. If you are looking for a free alternative,