Microsoft CSP is a per user per month subscription licensing program. The term of each subscription is one year when the subsciprion is created, though the customer can add/renew users and cancel the subscription without any penalty currently. The subscription will be auto-renewed as long as the SKU is still available in the CSP program, and the licenses do not expire as long as the subscription term is renewed.
There is also a price guarantee for the first 12 months when a new subscription is created. The customer will pay the same price that was established at the start and throughout the subscription term for a 12-month subscription. Prevailing pricing is used at the time each subscription is established. When an existing subscription is renewed at the end of the initial 12 months, the customer will pay the prevailing price for the following 12 months.