With newaudiotechnology.com we eventually switched to using USB sticks as dongles.

The reason is that we noticed some paying users were cracking it, too, because our licensing system didn't allow dual boot or having a workstation and a laptop.

But our licenses were supposed to be per user and people wanted to carry our software around with them. If setup correctly, the same USB stick is now used both as licensing dongle and it also contains installers for Windows and Mac.