The above author "docsavagemob" confuses shareware and donationware. He described the way donationware works.
Shareware means a limited program version - not fully featured. It may have a splash window on start, time- or use- limits or some features disabled in unregistered version.
I've downloaded RFA and run. Yes, it found many errors. About 300. And it fixes only 10-13 at a time. BUT THIS WORKS. I've spend about an hour to reduce the number of errors to 20. If you have a lot of time you can use this program not paying to the developer. But if you set much your time you will probably win paying $21 to keep your system clean and support future versions.