I have updated the plugin and a friend donated. Within this procedure I saw some pronlems:
I translated the plugin in the source in german. After the update my translation is gone. For every plugin which is in contact to the front-user, it would be very nice to have a separat translation file.
It would by very nice to choosen the "Donate" Button in the admin.
I've seen the "Recurring Donations" posibility. I changed to "Once". After I have saved the options, it shows me "1 years". That means "every year once a time" or "only once a time". What do I have to do for "Once a time"?