Can I reinstall windows without reactivating it?

I currently have Windows 10 installed on my desktop PC. Unfortunately,I don't have the activation code anymore. I upgraded from Windows 7 to Windows 10, so even if I still had the activation code it would be a Windows 7, not 10, activation code.

Now I need to reinstall the OS to a new HDD. I do not want to keep my data, I want to make a clean reinstallation.

Is there a way I can reinstall Windows 10 to a new drive while keeping it activated?

Is there a way I can reinstall Windows 10 to a new drive while keeping it activated?

Windows 10 uses a digital entitlement system. When prompted for your license key just skip that step. Once installed Windows 10 will automatically activate. Any activation issues that might happen can be resolved through phone activation.

I currently have Windows 10 installed on my desktop PC. Unfortunately,I don't have the activation code anymore.

You don't have a license key for Windows 10, your current key if you were to attempt to retrieve it, would be a generic key (the same generic key everyone uses). This generic key cannot be used to activate Windows 10 nor will it be accepted within the installation environment.

The only key that would be accepted within the installation environment and/or be eligible to be activated within Windows 10 would be your Windows 7 license key, which is printed on the COA sticker, that is on your device. While you could use this key, it isn't required, because Windows 10 will activate automatically.

Can I reinstall windows without reactivating it?

You are required to activate Windows, in order to use it, otherwise it will be in a trial/inactivated state. What that means varies from version to version.