I only use a phone but scrolling that page only gives me the option to purchase 1 of the 3 site supporter levels. Nothing about purchased upgrades anywhere.Did you see Account Upgrades (lower right when you go into your profile)?
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If you click that it will take you to this page:
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If you scroll down on that page, you should come to Purchased upgrades. Now, I will say that I'm on a laptop, so it may look different if you're on a phone, but if you switch to the desktop version (on your phone) then I *think* it might look the same.
No clue how to turn desktop mode on my phone