I don't know where you live, but in the USA, it's not an illegal substance, just heavily regulated. So, owning it isn't a criminal offense or anything but if you're purchasing from a legitimate source and not some shady online business, using a false identity in a transaction can be considered fraud, which is illegal. If the company should find out you're using false information and being shady, they may not accept to sell the SN or even alert the police, which will then land you in a wealth of problems and explanations. So I would think, it depends on your source. If it's shady, try not to use your real information as much as possible.