Ashmess, keep calm! I'm from Germany and I also got E-Mails from these solicitors and was in panic, too. They (also their "customer") tried to call me, too... I contacted my solicitor for this case and had no direct contact with the opposite side (no E-Mails, no phone calls). My solicitor said that E-Mails aren't worth anything, but he began to contact the opposite side with denying the accusation of using pirated software. At the end they showed their recordings (list with my MAC-Address, type and version of software, usage time) and my solicitor was denying that again. Finally they threatened with additional legal steps if my solicitor will not call them within a deadline of some days. My solicitor did not call them and said to me, that they can write what they have to say... We've not heard anything since 3 months. My solicitor said, that their proceed is absolutely unprofessional (E-Mails, force the opposite to call them,...). All this was before I found this forum. At the end I had to pay some hundred bucks to my solicitor for nothing. I think it would be smarter to not answer these guys... also cheaper ;-). What I researched: A logged MAC-Address is worthless, because no MAC-Address is logged by your ISP. They would have your PC physically in front of them to prove any legal or illegal usage of software. This step is in the meantime easier to realize in Germany, because if they have any solid suspicion a judge can order a house search/confiscation of your PC. All your ISP can do is to deliver connection logs with your IP-Addresses. So if ANSYS logged your IP-Address they have to hurry, because logfiles of your ISP are available only for a defined period. This period depends on your ISP - in my case my ISP is logging it for only 5 days. Deinstallation of ANSYS will not be "clean" enough, my recommendation is to set up a fresh OS. A good consideration for scared rabbits is to remove every piece of hardware with a MAC-Address buy new pieces of hardware, so a confiscation of the PC will show no traces... Very scared rabbits are exchanging their hard disk, too ;-).