Reloaded MAC OS and now CS6 product key is invalid

[Photoart]

Computer issues were solved by reloading Mojave. Photoshop CS6 worked fine for a few weeks then stopped. Asked for product key which it said was fraudulent. It isn't I purchased the product in 2015. I paid over $600. Now I am locked out. What can I do? (How do I find the product key on the app?)

[gener7]

This thread explains what to do:

https://community.adobe.com/t5/download-install/photoshop-cs6-will-not-accept-the-product-key/td-p/8...