I want to buy Lightroom as a one-time purchase. I'm not a fan of paying monthly perpetually for software, so I'd like to just pay once for the product. My only concern is, what are my options if I plan to change computers (from Windows to Mac) later next year? I don't want my license to not be compatible, forcing me to buy it again. So my question is, what are my one-time buying options that will carry my license over to a new computer if I change it?
You are allowed to move your license from Windows to Mac (and vice versa)
You may exchange the Licence for a different operating system.
Please have a look at the following article and you will get all the necessary information : Exchange a product for a different language or platform version