Cannot use full features of Adobe Acrobat Pro 9 despite having SN

[kChaste]

Whenever I use the program, a prompt pops up soon with pre-filled SN.

The prompt says "Please enter a SN now to continue using the product."

I clicked "Next>" button as the SN has already been pre-filled and encounter a second issue.

"The SN that you entered indicates that your setup is for an upgrade version of Adobe Acrobat Pro. To be eligible for this upgrade, you must own a qualifying product.

Select a product that you own and key in the serial number"

I lost my DVD case which was probably for Adobe Creative Suite 5.5 as it was 13 years ago and I don't have the SN anymore. I don't want to upgrade. I just want to use it Adobe Acrobat Pro as it is. Please help.

[Brad @ Roaring Mouse]

The idea I have right now is: If you had registered your CS5.5, you should be able to logon to your Adobe Account and find the serial number associated with it: https://account.adobe.com/products

Other that that, since Acrobat 9 is long now unsupported, you won't have much luck, even if you contact Adobe.

[kChaste]

unfortunately, I no longer remember which email was used to register this product. 

When I created a new account and entered the serial number, it says serial number already in use and I cannot download the old version any longer.

Is this a dead end?

[try67 · Accepted solution]

Yes.