Just about any of the audio recording or editing programs should work for you if you have an audio feed coming from a mixer into the sound board of a computer that is not also doing something else to the sound at the same time. Did your MAC come with a program called Garage Band? I have never used it but I gather a lot of people do.
I'm still not sure about the legality of using the program, but before Adobe bought the software, reworked it and named it Audition, there was COOL EDIT. Back then they would give you access to a slightly crippled version of Cool Edit for free. Think of it as a trial version that does not have a 30 day limit. You will still find copies of the old Cool Edit available for download on the Internet. I still have my copy which I paid paid for and they took away the "cripple" part. If you are not going to do serious editing, but just recording, the old Cool Edit would probably do well.
Many of the software programs you can get for free or very cheap has one feature that can be a problem: They record to a "temp" file. After two hours, when you stop the recording, then you have to do a "SAVE AS" which can take a long, long time. And remember, any kind of hick-up during the recording process or the SAVE AS process and you can lose your entire file. That is why I have this love affair with Total Recorder. You can tell it to start a new file every 3 minutes or every 7 minute or every 15 minutes or whatever. Without going through the SAVE AS feature, you immediately have a string of files. If you have a power company failure 1 hr and 53 minutes into your program that you are recording, you will lose only the content of the current short segment. That can, however, leave you with the task of putting all those short segments together as one two hour program. the .M3U process should handle that well if you are recording and .mp3 files.
When I have mentioned this automatic recording to short segments in the past, others have offered the names of other programs that will also do this, but i don't remember the names.
The Audacity program is free, and for RECORDING ONLY it is a great program. I don't feel it is as robust as Audition for "radio style editing" but as a recording program that will allow you to edit out the pre-roll that you captured before your 2 hour program began and trimming off any content that was captured after your program ended, Audition plays with the best of them with that kind of editing.
If you plan to do the recording on what amounts to a stand-alone computer, think your way through the process. When it comes time for playback, will you be able to play it back from that same machine back into the mixing board or into the automation computer, or will you need to be able to transfer the recorded program to another computer for playback?