Is the Data meter going to effect my job?

I'm a little upset here, I was NOT informed of a 300gb limit when I signed up for Cox. seeing as you own a monopoly on my current residence I have no other option but to get internet from you guys which isn't a problem unless me going over my limit is going to be a problem, I do live streams on twitch tv as a JOB online and I can't have this data limit effecting my work.

Please let me know if this limit thing is a big deal, I'm at 301 of 300 and still have 6 days left in the cycle, I will need more every month for my work and there's no way I can afford a bigger speed package. Thank you for giving me any info.