It is going to depend.
Was that HDD formerly the C:/ of the computer you want to attach it to? If so, it may be licensed for your hardware despite the change.
I assume by "USB adapter" that means you have put it in an external hard drive shell...
Enter your BIOS or UEFI and make USB a top boot priority. Then at startup you should be able to follow prompts to boot from that drive.
However, the Windows install on the portable drive may not recognize the change in environment. Also, if the whole PC you are using is different from the one which you pulled the legacy drive from I would not even give it a chance.
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