I like to buy the gold club, but I have a question.
After 12 month I'm no longer able to update RSVP, right? So I have to pay 100 Euros again?
That is the case BUT you may not need to update the addon for a while - the most likely reason for needing to upgrade is when you upgrade to a new Joomla version that is not compatible with the version of RSVP Pro you have on your site.