Reviewing through your description, the message interceptor might meet the functionality you are looking for. For more information on this, check out - Configuring Interceptors
This allows you to configure a posting limit on content, where a user will see a message similar to:
if they exceed that rate.
However, the feature of allowing a user X amount of posts is not currently available in the product. As such, if you are interested in this type of feature, I would recommend submitting an idea to the Ideas for Jive space where our product managers review through to rated ideas when considering features for future releases.