if the key was a "system builder key" yes there will be issues I have plenty of issues with those ebay keys. Ive never has issues with a retail version of Windows 7 Ultimate, the same key has been used on 3 different PCs when one bit the dust or was replaced.
One perk to the embedded keys, if you drop your laptop and toast the HDD, when you get a new HDD just download windows 10 from Microsoft and install it, once installed it will automatically activate windows with the embedded Key. handy for these new laptops without separate recovery discs.