Because ongoing software development and support costs $$. Someone has to pay for that. Software licensing fees is the mechanism of choice for mass market products. With one-time purchase products eventually the end of life point is reached where you can no longer get support, updates, etc. With free products support can be iffy at best, and they do have a habit of coming and going. You get what you pay for, and you don't get what you don't pay for. Someone who has spent hundreds, if not thousands of dollars should budget for software maintenance. It's like buying a car - you need to consider the interest (if getting a car loan), the cost of regularly scheduled maintenance - tire rotation/replacement, shocks, brakes, oil and fluid changes, cost of gas etc. It would be wonderful if all of those ongoing expenses were bundled into one price, or better yet, completely free, as well as the car - but sadly they are not.

Hello Hoggers:
I work on a Mac and had been using Lightroom 5 for years, first for cataloging and organizing as well as editing. For the last couple of years I've been using it mainly as a DAM while using Luminar 4 for editing. I recently upgraded my OS to Catalina which disabled some of the functions on my old version of LR. I have uninstalled LR and figured I'd use Luminar 4 as my cataloging program. It leaves a lot to be desired in that respect. So, I'm looking for an alternative. I do not want to go to the subscription for Adobe creative cloud as I have never used and don't wish to learn Photoshop and you can't get LR alone. I've been doing some internet research and have looked at Capture One (rather expensive) and ON1 Photo Raw (a little more reasonable). Both of these also have editing capabilites - not necessary for me but a nice bonus. Reading about various programs on the internet is one thing but hearing real photographers experience with these programs is better. The ability to use keywords is important to me. Any advice and suggestions would be greatly appreciated.

Because it's sometimes false economy if you don't look at the whole system lifecycle cost. The OP reported that his copy of Lightroom 6 wasn't fully functional anymore. From time to time, you have to pay upgrade costs in the perpetual license model, or you face a number of risks, such as your operating system won't let the software function, or it won't read your new camera's RAW files. Sometimes developers fix troublesome bugs, introduce highly desirable new functions, or improve the software's performance in their upgrades and bug fix releases. Sure, some will respond saying they've used product X for 10 years without incident, while others, like the OP, will report frustrating problems. Free software? I've tried some - quality varies, documentation is not up to commercial standards, and, except for user groups, there is no support. My suggestion to the OP was to try the LR Photographer's plan and see if he likes it. If not, try something else.