I'm a little bit disappointed about Parallels..
B2T: I solved the problem by changing the subscription to "none" (don't know how it's exactly written in the english version of Plesk). After this, I was finally able to change the subscription length to "endless" and I got rid of the daily...
Subscriptions expire every day
This seems to be a real newbie-problem, and I'm mortified asking this question - but I could use a little bit help on that problem.
I'm using Plesk 10.4.4 (#19) on Linux Ubuntu.
One year ago I started using subscriptions and service plans just to test these...