I've bought these kind of keys (Windows 7 Ultimate) twice in the pass.. the first key i used for 1 year then it got blacklisted as being counterfeit. The second key lasted for around 8 months. I tried to contact the seller for a fix on these matters but he neglected to refund nor issue a fix by saying that he no longer sell these keys. Reporting to lelong was futile as well cause the transactions were made pass 3 months.
They seems to get the keys from a key-generator of sort. Well... i wouldnt recommend getting it.