Question

I have developed an iPhone application, which is already inside iTunes available for download.
Apple also gives you access to the developers member area and many other tools.

Does anyone know, what happens if I decide not to renew ? Does this affect my existing app from download or function in existing devices? Which are the consequences ?

Answer 1

From the iOS program support center

What happens if I do not renew my iOS Developer Program membership?

Once your membership expires, your apps will no longer be available on
the App Store and you will lose the ability to submit new apps. You
will lose access to pre-release software, the Apple Developer Forums,
Developer Technical Support, and the Certificate Utility. In addition,
your existing iOS Distribution certificates will be revoked and
invalidated. Finally, if you enrolled in the program as a company, you
will lose the ability to manage your development team.

You will, however, retain your status as a Registered Apple Developer
and will have access to free development resources.

I think that says pretty much all, the users that downloaded your apps will still be able to use them I’m sure, but the apps will not be available on the store anymore.