Use within my circle of friends

Hi there!

I just set up a new site which is only available for my friends and which should replace the use of "doodle". In average 2-3 events per month by 10-20 users.

I ran across JEvents as a calender for this purpose. What I was missing is the function so subscribe to an event.
I found out that the "Simple registration module" is what I need in addition and this would cost me 40 EUR.

My question:
Are these 40 EUR per 6 months a one-time-fee (means one-time-download and longtime use without the right for further updates) or do I have to pay every half a year for it's use?

In last case I would delete it right away since this is much to much!

Thanks for your answers!
Best regards,
Knocky7