Currently, we do not impose a hard limit if a user accidentally or intentionally added additional data sources that exceeded their plan's limit. It also won't be auto-upgraded to the next higher one.
We allow this behavior so that the user can thoroughly test the various data sources we support before finally committing to a change. Also, keep in mind that other features of the platform are still in effect, depending on their plan.
Once the user is happy with the result, we expect them to contact us to discuss upgrading their plan. If they fail to do so, we will contact them instead. We can identify customers that exceeded the limits of their plan.