Windows XP XP for an offline computer

I have an old Acer computer that I would like to run for 5 different things in Windows XP. My biggest interest is shown in the image. It's a telescope mirror analysis program which is called FigureXP. I have an XP install disk on the way. Most of the time the computer will not be on and I can import programs from disks I have. The big question is how to get around the dial up registration. I didn't want it shut down after 90 days. Any suggestions (except windows 10) would be appreciated. Thank you
P.S. Not going to browse with this boat anchor