Windows 10 - Activation

I have a HP Stream PC13 which has 35 GB HD and 2GB of RAM - so things that go on it have to be watched. I bought it in May to use for studying for myself. It had Windows 8.1 and I reserved Windows 10. I thought I activated Win 8.1 which was on it, but I can't be sure. I tried 4 times unsuccessfully to load Win 10 from a USB within win 8.1 put on there using the MS Media Creation Tool 64. Finally I loaded Win 10 by using the HP Utility to boot up from the USB Drive. Now the software is asking for a Product Activation Key. I finally went to the MicroSoft Store and they found my Old Key in the Registry. When I used it Windows 10 won't Activate. I am not sure I activated if I did win 8.1 correctly, but the registry has a key. It will cost me time and $50.00 to get a Win 8.1 restore USB from HP. It will cost $119.00 to get a Product Activation Key from MS. I am getting an error 0xc004f050. I read to obtain a tool in some of the windows 10 forum entries and that error could be corrected by that utility. I went and did it and it corrupted my install. I asked for a refund. I am not trying to point any fingers, I am just trying to solve this issue. What is the most cost effective way to solve this mess? Also I read through a lot entries before I asked this.

Oh dear ,It looks like you've tried to clean install without upgrading first.
.Hopefully your notebooks recovery partition is still intact so you should be able to recover it to the state it was in when you first bought.
It looks like its just a matter of unplugging the ethernet cable if its attached, plug in the power supply and start the notebook , as soon as it starts tap the F11 key to get to the recovery screen.
View the appropriate video on here http://support.hp.com/gb-en/document/c03489643

Google and find Windows 8 or 8.1 OEM ISO and make an install DVD. It doesn't have to be for your specific computer, it can just be plain vanilla Windows 8 or 8.1. Install Windows 8/8.1 using the DVD. Google slmgr to see all the commands available - specifically you want slmgr /ato (online activation) slmgr /dlv (see detailed license information) and slmgr /xpr (to see expiration information). Once you are sure you have a properly activated Windows 8/8.1 then use the Windows 10 Media Creation tool to upgrade to Windows 10. If you are asked for a Windows 10 key during the install/upgrade process, click the tiny print that says "Skip", "Skip this step", or "Do this later" ( or something similar). If you have problems with Windows 10 activating, after a few days, call the Microsoft Activation help number.

I have a Windows 8 OEM install disk that I made from an ISO, but I can't remember where I got it from because it was so long ago.