Using the W10 key on your old laptop.
Using the W10 key on your old laptop.
I possess a Windows 10 activation key from my previous laptop. After removing and clearing the registration on that device, I still face issues activating it on my new PC. The system indicates a digital license is missing and insists on purchasing a new one. The SLUI 4 method is no longer functional, preventing phone-based activation. Microsoft support may assist, but reusing the old key is uncertain—some users rely on unofficial keys or key generators, though I’m unsure if these provide updates.
Likely an original equipment manufacturer key, preventing transfer
We shouldn't talk about keygens since that involves illegal activity. Regarding inexpensive keys on eBay, many breach the Microsoft EULA because they're typically unauthorized resale items. The safest option is to buy a key from the official Windows store, a nearby store, or Amazon.
Aligns with @Slottr's view, likely the issue occurs with OEM keys. Another chance is if you've ever run pirated Windows 10 on that machine, the activation might say "Could not activate your license due to connection issues with the MS server." Ensure 'Windows Update' and "Software Distribution" services are active. Confirm Windows receives updates correctly.