I have an Adobe subscription. Every time I try to purchase a stock asset at $2.99, I get the Choose a Plan prompt. I choose a plan and then "Good News You Already Have a Plan" - okay great, can I purchase the image now? Nope - RIGHT BACK into the Choose a Plan prompt.
What an incredibly frustrating experience, and even crazier I have to come to the forums to get help? That's LITERALLY my only way to get any help with this?
I see you have an Adobe account under the same ID as with forums. I did go through your account details and noticed that you were able to purchase a Stock asset on 5th of March 2018.
Can you please be a little more specific about the issues that you are facing related to your Stock subscription?