Your images are in folders on your hard drive, not "in" Lightroom. All of the adjustments you have made to your images are stored in the catalog, which is a user file that was generated on your computer. If you downloaded the standalone licensed trial version, and you are wanting to activate it, you can make your purchase directly from Adobe and simply use the serial number to activate the trial version that you have installed. If you made the mistake that many do, and have installed the creative cloud version but want to purchase a standalone Lightroom license, then it will be necessary for you to uninstall the version that you have and then install from a different website. In either case, your images and all the work that you have done will remain intact. You won't lose anything.
Thank you very much. That is very helpful.
HHaving very recently gone through this I confirm what Jim said. I had the 30 day trial downloaded from the CC but wanted the perpetual license version.
when I installed the perpetual license version it was seamless - picked up my Trial catalogue immediately and now I'm on the foothills of the learning curve. Good luck with it