Limit front-end submitted posts by role

Right, I know this question has been asked, but, none have provided me with a workable solution, hoping someone can help.

I created a property listing site using the plugin Essential Real Estate. The plugin does offer a solution to limit posts using packages, the problem is that I need individual posts to expire in 6 months, the package solution expires the whole package.

So what I want to attempt is to place registered users on roles and them limit the number of posts each role can make.

I've tried plugins but none seem to work, I suspect this is because posting of the properties takes place via the front-end.

Really hope someone here can help, I'm rather desperate.