If financial difficulties are the issue you do have the option to pay $10 instead of $20. If, as with many parents, transferring CC info over the Internet is not an option, there are other ways to pay including fax and postal payment (although postal payment is subject to an extra $2.50 charge + VAT - another reason there's an option to pay $10 instead).
Also remember that it's a one time registration. Every single future update is free - there are NO catches, gimmicks or small print. Register now and you can still be using a registered version of mIRC in 10 years time. Once it's done, it's done and forgotten - putting life in perspective, what's $10-$20 for a lifetime registration?
Also, whilst your dad is correct it's unethical to "crack" mIRC, it's understandable for people not to be always be able to pay instantly, the day the 30 day period is up. As far as I know, Khaled understands this - If it will take you another 1/2/3 months to convince your dad, or get the money yourself, then that's acceptable.
Might be worth mentioning these points to your dad and see if he can make a better judgement - Having started out on a java chat client for 2 1/2 years, I wouldn't wish it upon anybody!
Regards,