i have a macbook pro with yosemite osx installed. photoshop cs4. i get this error message at least once a day, if not more. it usually opens without a problem after closing the program and reopening it, but i am still concerned about this.
i'm not sure what other information is needed, so feel free to ask for more specific details.
This is a very common error with CS4 and Mac OS
You can uninstall/reinstall CS4 or if you want, open Terminal and run the LicenseRecovery.py python script that should fix it.
I am having the same problem with CS4 and I have MAC OSX 10.7.5
The Licensing Repair Tool does not work on my system. What else can I do? I don't know Terminal well enough to find scripts.
The Repair app only works on 10.6
Here's a screenshot guide to the Terminal Script. Start at post 11. Review it and give it a try. Otherwise, you can uninstall/reinstall CS4.