Typical signs of fake offers
- Unrealistic price. A price far below the usual market level is the clearest warning sign of a problematic offer.
- Wrong key format. A genuine Microsoft key has 25 characters in five groups of five. Other formats are suspicious.
- No invoice, no support. Anyone who fails to provide a VAT invoice on request and cannot be reached is not offering a genuine business relationship.
- Pressure and urgency. Countdown timers, only a few left, buy now. Reputable providers don't need such tactics.
The only definitive authenticity test
Microsoft does not operate any public database in which you could check a licence key in advance. Checking the format helps rule out obvious nonsense, but proves nothing.
The only definitive test is activation. If Microsoft's servers accept the key and report the software as activated and genuine, the licence is valid. That is precisely why reputable providers offer an activation guarantee: they take on the risk should activation fail.