This is a common question with "free" platforms/apps. How do I know if my users are using the platform and for what purpose. I am making the following assumptions about your product
1. Your product is in beta testing and you haven't started monetizing it yet
2. The apprentices that you speak of are freelancers who will use your platform to complete the task and the company who uses these freelancers will pay platform fees.
If I am wrong about these assumptions, please let me know and I can approach the question differently.

There are a few ways you can approach this.

1. When someone signs up or downloads your application, clearly identify that they are participating in the beta test of the product. They agree to submit usage information every day/week/month. You can then reach out to them to collect data

2. Send surveys to users to get feedback

3. Analytics if there is a way for you to monitor online how they are using your platform

Essentially, there is no Free Lunch. If they are using your platform for free, they agree to provide data in return.

Happy to chat more if you'd like to figure out a clear strategy of how to engage with your users for data collection. I specialize in customer discovery and have helped many companies with early stage development and market validation.

Best of luck with your venture!
Fehmida