Hi Guys!
Newbie here.

I have a question.
How would the Dev know that it is "you" who send the payment during ICO?
I saw their ICO page and it only said "Send your ETH only to this address". It doesn't even ask any information about you.
Thank you in advance!

The token would be sent back to the address you sent eth from. so it's advisable to send eth with the address you wanna receive with.