I thought I had read the offer ends today but not sure since it isn't posted with the promo info button. These are only one line plans. According to the info about the promo there is no restrictions on how many you can have. Each line of course will need separate accounts and email addresses. Visible does reserve the right to deny this offer to customers so keep that in mind.
Not 100% sure what you are asking. The bring your own phone promo is for 12 months, at $15/month.
The terms and conditions are:
New members that activate via "Bring Your Own Device" or BYOD, via either eSIM or pSIM, and port-in their number, may use eligible promo code 15OFF12 for a $15 per month discount off the standard Visible+ $45/mo or Visible $30/mo service cost for each of the first 12 months of service. Standard costs of service apply starting with the thirteenth month. Promo code is for one-time use only, and only one code may be applied per customer and/or per account. Promo code is not transferable, not redeemable for cash and has no cash value. Member must maintain service on the Visible+ $45/mo or Visible $30/mo plan for twelve consecutive months to get full benefit of the promotion; no value will be provided to the member for unused promotional months if an account is terminated or migrates to an ineligible plan prior to the twelfth month of service. Promo code 15OFF12 applies to service charges and the member is responsible for all applicable taxes and fees.
Promo codes may not be combined with any other sale, promotion, discount (such as Bring a Friend* discounts), code, coupon. Void where prohibited, taxed, or otherwise restricted. Limited time offer.
Visible reserves the right to change or terminate this offer at any time, with or without notice, including for any violation of Visible’s terms of service.If Visible, in its sole discretion, determines that a member has engaged in abuse, misuse, or gaming in connection with this offer, or that the member intends to do so, Visible reserves the right to disqualify the member from this promotion
You can read more here: https://www.visible.com/shop/bring-your-own-device