My PC is dying and I am getting a Mac. 1) While transferring all my files from the PC to an external HD I see I have many Lightroom backup files. Do I need to keep them all or just the most recent? 2) Will I need to keep the Lightroom Catalogs as well? 3) How do I transfer my Creative Cloud subscription from my PC to my new Mac? Thanks!
1) If you are satisfied that your catalog backups are sufficient, you can delete the rest. Whether you keep only the most recent depends on how you've designed your approach to backups. For example, I keep a few recent ones and then maybe one backup for each month after that. That way, if data for several images becomes corrupted but I don't notice it for a couple of weeks or months, I can still go back far enough to find the uncorrupted versions of those image edits.
2) You must always keep any Lightroom catalogs that contain irreplaceable work. The catalog contains all your edits and all your organization, and the catalog file format is the same on Windows and Mac. When you copy your Lightroom work from Windows to Mac, you must copy the catalogs and the images. The previews are expendable because they can always be regenerated, but the catalogs and the original images they refer to must be preserved.
3) You can use a Creative Cloud subscription on any two computers you own, Windows or Mac, so it isn't really a transfer. You just install the Creative Cloud desktop application on your Mac and sign in, and then it will let you install any software your subscription entitles you to. Then, whenever you feel like it's time to decommission your old computer, you can sign out of the Creative Cloud desktop application on the Windows computer. That will free up your second activation again. In the meantime you are legally entitled to run your Creative Cloud software on both your Windows and Mac computers if you want, just not at the same time.