Interesting, seems like it overwrote at least some of your Cubase 7 trial. That’s not strange because Cubase 7 and Cubase artist 7 are exactly the same, it’s the license that determines which features are available and which aren’t.
The question is, does it work well? Do you have all the presets for plugins for example? If everything is fine, I guess you could just go with it. If you want to be sure, you could also uninstall Cubase 7 completely (both artist and the trial), then pop the disc back in and install Cubase artist 7 again. No need to do the license activation etc again, that’s all done and stored on the USB key. As long as the latest version of the eLCC is installed you can uninstall/reinstall Cubase whenever you like.