What does 'registering' mean? 
Two things: 

1.  To send me your data, so that I could keep a IsiPlot users database, to be able to inform you (if you like) about new releases.
2. To contribute to IsiPlot developing-enhancement and to Plans collection management with only a few money (I suggest 10 euro or the equivalent in your local currency), so that I could regain the money I spent and go on with the development. 

You can send me the money in a closed envelope with your registration data (see Registration-Registration form in the menu of IsiPlot application, not in this web site) or use PayPal clicking the botton below:

I have a little problem with international cheques, I have a cost of about 8.5 euro/US$ to cash them.... too much!

I want specify that this money is considered a kind of voluntary offer so that you can contribute to IsiPlot improvement. 
With that money you don ’t buy a license of an application, I don’t sell IsiPlot. 
And, if you have a better idea to contribute, write me. I think my request isn’t exorbitant, but, if you think so, write me and tell me your opinion. 

If you have 2  PC no problem, I then will send you the registration password for your second  PC. The registration is to YOUR name, and so YOU can have password for YOURS PC. I think that isn't right a thing to ask money for every PC. I think this is the good approach to software distribution. If you have 2 PC you'll use them only one at a time, I suppose!
But please, don't ask me passwords for yours FRIEND!  
If you ask me 20 passwords in a year, I can suspect that you are distributing password to your friends, and I will stop to send them to you.
So this way to manage registration requires that users of Profili are as honest as I'm. Please don't take advantage of this by distributing passwords....

  You can contact me by 

Duranti Stefano 
via della Casazza, 43/B 
32032 Foen di Feltre (BL) - ITALY 
E-mail st.duranti@tin.it / info@profili2.com 

I started also a mailing list named ‘Software Profili’, where all users can exchange opinions, tips and plans. If you like subscribe it send a message to software_profili-subscribe@yahoogroups.com.
The subscription is free.