I believe it's tied to the CPU?
I don't think macros or automation are what we'd be after, but mainly the ability to broadcast modifier keys to all machines, the option to have some or all modifiers on some or all machines at once would also be excellent. Other than that, how is it different to AHK? (which can be used to bot)
I would consider paying for a tool if:
It did what I mentioned before with multipliers, ie alot of flexibility from them.
Did not incorporate anything like automation that could be considered a rule breaker (this is what I dislike about AHK, that grey area)
Has decent support, tutorial on setup etc (even just a notepad/pdf file with a walkthrough on setting it up etc)
A discount if you purchase more than 1 copy would be good, $10 once is fine, but tied to each machine and I'd need 3 currently, starts to add up...
I have no problem with someone charging for something they've created, after all you've spent time and effort to create it, that time is worth something, but, there are free tools that do the same or at least offer similar functions, you need something to make the fee worthwhile. If you can do some or all of the mentioned above, you'd be well on your way to offering those incentives imo :)