Daily and Monthly Identities work the same way. You can keep either for as long as you like, and each keeps the same IP for as long as it exists. The difference is in billing: Monthly Identities are paid for upfront and stay active for the full month, even if you remove them. Daily Identities are charged by the day and billed at the end of the month. You can remove them at the end of any day. Monthly Identities cost less because of the added commitment.