purchasing add on

hi pickplugins,
i am using your job board manager plugin and it really helps! i want to purchase some features and want to know that is there any pricing that includes all add-ons? or should i buy them individually?
second, on my your plugin add ons section, there are some features with button, install, but when i do so, it failed to install the add on. what is the problem?
kindest regards,