Some insurers offer their policies with deferred payment as an option. In case of a deferred payment, the risk coverage immediately starts and the buyer is allowed to pay the insurance fee later (within a given time period). If the insurance fee is not paid, the insurance coverage is annulled.
Deferred payment is comfortable in cases when the insurance coverage is immediately needed, but there is no easy way to handle payment on the same occassion - for example, in the case of a buying a used car from a private person and securing insurance online.