Windows uses two activation flavours: digital license (linked to a Microsoft account or motherboard) and KMS/MAK key (corporate, tied to a server or product key). They behave differently after an HWID change.
A digital license bound to a Microsoft account survives any HWID change — Windows just re-checks the account at next boot. If the account is signed in, activation is restored automatically within minutes.
OEM activation pinned to motherboard hardware is more delicate. After SMBIOS rewrite, Windows may report "not activated" until you run the activation troubleshooter (Settings → Activation → Troubleshoot). Usually 1–2 minutes and you're back.
KMS keys handle HWID changes the easiest — they're tied to a server, not local hardware. Just re-run slmgr /ato after the change.
The general rule: link your Microsoft account to your Windows install BEFORE doing any HWID change. It takes 30 seconds and gives you a frictionless reactivation path.