Many of those specializing in media streaming will charge for the max number of simultaneous users.
In the Abacast case, all plans comes with 50,000 listener hours a month. So based on that, each plan can support up to (50,000 hours / 24 hours / 30 days) = 62 listeners maximum listeners per hour if they listen 24/7 for the month.
Of course their model makes sense if you do not have constant number of listeners and it peak at certain time of the day or day of the week such as weekends and slow down at other times. It effectively means that you can hundreds or thousands number of users if say your show is only once a week.
As to whether their system can handle it, I wouldn't know. But it looks like a nice plan from the outside.
Assuming these prices are monthly (cudnt find it mentioned anywhere).. won't it be cheaper to go for a VPS and set up your own streaming server? I have no idea abt streaming so this might sound weird.. but was just thinking about the possibility..