Share Project. - User Restrictions

I would like the abilty to set a limit on the users i invite to websites. For me it would be. 1 user in this case a client. I would like to be able to limit them on how many edits they can make to the site. Im not sure what would work best but easiest. may just be number of edits and a duration - for example 10, 20, 30 edits per month/ week. Others may want a cost but this is variable. More to stop large editing sessions or mass page building.