How can I reinstall trial software?

I formated my computer and then reinstalled some trial software I was testing out and now they say they are expired. I was just wondering if there's a way to get remaining time or to get the programs to reinstall. To be honoest im not sure how it even know's the software was there, when I formated I deleted my partitions and recreated them in different sizes, doing a full format to all the hard drives. I've looked at a lot of different "answeres" that say it's in the registry, but I deleted the regestry when I formated didn't I? (Part of the reason I format is to get things working more quickly again)