Which addresses are mine
Where your plan lists its addresses, how long they stay, and what happens when a plan expires.
Which addresses belong to your plan
Every plan lists its own addresses. Open the plan in the dashboard and you see how many you have, the exact list, and the date the plan runs until. The copy button takes the whole list at once, so it goes straight into your tool without retyping.
They stay on your plan for the term. The addresses are assigned to your plan for as long as it runs. They do not rotate underneath you, which is the point of ISP addresses: a social account or a login that expects to see the same address keeps seeing it.
What happens at the end. When a plan expires the addresses go back into the pool. Renewing before it lapses keeps them. Letting it lapse and buying again gets you different ones, so if a specific address matters to your setup, renew rather than rebuy.
If one stops working. Report it from the ISP page rather than opening a ticket. The form takes the addresses and a short note, and it reaches us with the plan already attached.