Since yesterday every time I want to update a plugin, Wordpress asks me for the FTP data, which I never had and never put because I use an instance ec2 and I connect to the FTP with the PEM file. Does anyone know why wordpress asks me for this information that I did not ask before? Thanks!
That means that Wordpress itself is not having permission to update them.
Either the plugins folder (or their parents) do not have write permissions or the directories and files do not belong to the user that Apache is running with (www-data or apache depending on the operating system).
The WordPress recommendation is that your folders have 750 (or 755 only if necessary), and 640 (or 644) files. That would allow WordPress to update your plugins and files.
To modify the permissions, you can do it from the control panel of your hosting, or use an FTP program like Filezilla, where you can right click on the file or folder and choose "Change Permissions".