Solution for Magento 2 Community Edition (CE / Open Source)
If while saving Magefan extension on Magento Community edition you get the error "Product Key is empty or invalid. The extension has been automatically disabled." and you don't see any Product Key field, as on the screenshot:
Attention! Magefan Community is not a Magefan Blog, it is a separate module that used together with Magefan Blog.
To check the version of the Magefan Community extension you can take a look inside one of these files:
If you have an old version, then you need to update the extension.
If you have the latest version and the issue is still there, please contact us.
Solution for Magento 2 Enterprise Edition (EE / Commerce)
Magefan Blog is paid for Magento EE, but until Blog v2.8.10 we didn't require a product key. In version 2.8.10 we added the product key field. If you used a free community version you need to purchase Magefan Blog extension for EE to be able to use it.