Also, the version I used took a screenshot every 10 minutes; if it happened that something unintended got there, I had the option to delete that screenshot (losing these 10 minutes, naturally; or having to submit them without a screenshot, which was a separate "manual" category).
I worked as a freelancer for years, and I would have refused to work for someone that required me to install tracking software.
If it's possible at all, I would work on trying to bill daily or weekly instead of hourly if I were you.
Also, I my case it was a requirement from the site (Upwork); in return they guaranteed the payment, that is, if I provide screenshots, I get paid by Upwork even if the customer doesn't pay. When I started a few years ago it was very reassuring, although I don't think this actually happened with my customers.
They don't. Not by a long shot.
Also the software now has your data as well so you have to trust a 3rd party company in addition to the one you're doing business with.
In addition, the screenshots are getting shared around the company increasing the risk even further.
A huge chunk of my time is spent at the white board.