I Work with dozens of people using TV free and I’ve never once seen a time limit even though we’ve left connections open for more than 24 hours straight and connect several times per week/month. I’m not seeing any user facing docs indicating this policy, either. I wonder if they’ve flagged you for commercial use based on IP or number of machines or maybe your account is registered as a business?
There are other truly free, but less capable options, like GoToMyPc and the like; it really depends on what you need for features and how you prefer to interface.
EDIT: silly me, my search skills are waning; I won’t embarrass myself further by posting what I submitted on my last attempt.