What’s happen when we reach the 50 limit of the free plan ?
Here is the the answer you are looking for - https://help.collect.chat/article/show/60991-what-happens-when-i-cross-the-response-limit.
In a nut-shell, the bot works fine and continues collecting the data. However the excess responses will not be visible to you. An upgrade to any of the paid plans, will increase the limit and you can then export the responses you missed out on.