Can I access my submissions if I downgrade my account?

What if I cancel my subscription after collecting the data that includes the attachments and form data.

Am I still able to access the attachments after my subscription ends?

Yes, you are still able to access your data, but take into account that the storage limit will be applied since you will downgrade to free, you will be able to download your data as the oldest submissions will be deleted from your account, you are able to store 500 only while using the free plan; however, your submissions will be restored if you upgrade.

This guide will help you downloading your data: https://www.jotform.com/help/374-How-to-export-all-of-your-data-at-once 

Hope this helps. 

You said oldest submissions will be deleted but if I upgrade again can I access those submissions?

So basically they are not deleted but are hidden/locked until I upgrade again, right?

Yes, if you upgrade you will recover your submissions again. If you would like to keep your submissions on your JotForm account available, then you may purchase the Storage plan, you should find it on our pricing page once you receive the alert about the storage limit passed.