Default administrators in the organization will be notified when 75 percent and 100 percent of their credits have been used and when a member has used 100 percent of their credit allocation limit. If your organization uses all of its credits, the subscription may be suspended or restricted, or go into a negative balance, depending on the subscription type. Subscriptions can be reactivated by purchasing additional credits. While an account is suspended, access to services and other items is temporarily unavailable, but the content is not deleted or removed from the system. With a restricted account, access to premium content and functionality is limited, but the account remains usable.
Could be you have an educational account and they have terminated your association with it at the end of term or upon graduation