I suspect my old SATA SSD is dying and I would like to move my Windows 10 to a new 970 EVO I purchased. My issue is, I no longer have the USB installer or key for my current copy of Windows.
What are my options?
A few things. First, you can redownload and create your own Windows 10 install media by using the Media Creation Tool and any USB drive at least 8GB in capacity.
Second, you have the choice of doing a fresh install onto your new 970 EVO. Since the motherboard hasn't changed, it should activate without issue. I would also ask if you use a local account or Microsoft account to login to your machine? Microsoft seems to "store" your Windows 10 keys if you use a Microsoft account.
Another option if you don't want to lose anything on the current drive is to clone your old SSD to your new one but as you said "it may be dying" so I would backup anything important before doing so. For cloning there are a bunch of tools, free and paid. If you want free, I would go with Clonezilla. And if you have some spare cash, I use Aomei Backupper Pro, as it allows you to clone with SSD alignment.