You activate online usually and have to enter credit card details, addresses, etc. If you use a one time card, and an address that doesn't match your name on the account you have to make to you in the personal database, then your sim is blocked until verified. Verification is usually sending them images of government issued ID.

The sim can usually access their networks to create the account and verify without using data. Meaning if it truly was your only device, it will allow you unlimited data to use the ISP website.