Awesome to see you are doing this for your clients. I am in a similar business so I get it.
Just a few things:
I’m offering a service to clients where I set up their Facebook ads. Instead of charging a flat fee, they can pay me on commission from sales referred from the Facebook Ads I setup.
I see a huge risk in this for you since whether or not your clients get leads depends on many factors – their products/services, market fit, pricing, seasonal (if any), and many others.
If you had to do this, you could just sign up with an affiliate CPA program and you’d at least have everything tracked and managed for you. Clients are risky as it is, and this is a level of risk you’d rather not take.
Can anyone recommend any software for tracking sales and commissions made by the ads I have setup?
But if you still have to do it this way, I agree with @Hristian. Use a tool/software that helps you setup affiliate programs, or have your client set up an affiliate program.
I usually integrate Google Analytics and use Google Campaign URL builder, but is there a software that track leads and sign ups to show clients they are the direct results of my advertising?
There might be a way to setup exclusive Google UTM parameters to make this work for you (and track everything in analytics), if this is the route you want to take.