Fairware has been phased out and I don't accept monetary contributions anymore. All software from Hardcoded Software are without limitation and free to use (... among other freedoms that open source provides).
If you're feeling like contributing money for this software nonetheless, I encourage you to contribute 20$ to a non-profit organisation of your choice. If you're not sure which, I would strongly recommend the Electronic Frontier Foundation which is pretty good at defending our digitals rights and fighting the bad guys.
If you're stuck with an old version of Mac OS X, you might have to use older versions of HS software, and these versions come with shareware/fairware limitations. If you're in that situation, use the keys below:
dupeGuru Registered email: clapperliar Registration code: 220c84997bc6a45ec61da6838e9f0814 dupeGuru Music Edition Registered email: snowdenpatriot Registration code: 4c0f7d0dcff24b5d14d0dda51b610bfc dupeGuru Picture Edition Registered email: solongandthanksforallthefish Registration code: 33e3897d4693c8b76982b2ec9adfb18e moneyGuru Registered email: nsabad Registration code: 551c273005167bf2b06fe737d9774038