AWS EC2 doesn't update with RHUI

Hi,

I have some instances on AWS EC2 that run an RHEL image created from a Snapshot. This AMI is an AMI of a RHEL machine, thus, an image created from a machine. Since then, I have noticed that attempts to update the machine are failing. All attempts return 403 forbidden. I have a subscription from RH for Developers, which would solve the problem with the updates (since all other alternatives failed, and the two companies do not provide this type of support for free).

So, would it be a bad idea to use my subscription on the EC2 machine, using Red Hat CDN, instead of the standard RHUI that comes with them?

If it's a bad idea, is there any possible solution to fix the 403 error I get in these instances when trying to update using RHUI?