Hello @JorgeC, thank you for joining our forum!
You can find all steps for Downgrading from Enterprise Edition to Community Edition here.
For more questions regarding our licensing model and what happens when the subscription expires, you should check out our FAQ section.
Finally, for the updating guide - please see the Update page where you can choose preferred installation method or our official documentation where you can find more detailed instructions.
Hopefully, this answers all your questions!