Based on the available information, it appears that ChemDraw Pro is distributed as shareware, not freeware, which means that you can use a limited version of it without paying for a limited amount of time, but if you want to unlock its full functionality, you're going to purchase a license. You can acquire the application from its developer's website.
In case you need a free alternative, I noticed that the application also has a web-based version called ChemDaw Direct, which has a limited functionality, but that could still be useful as well for your needs.
