THESI EvS ESSENTIAL is a product offered to micro enterprises that have planned investments on software only for the purchase of basic modules and that, at the same time, want to use a quality product that guarantees them excellent performance. The product is flexible and scalable as it is able to reach higher levels of structure such as THESI EvS BUSINESS UP and/or THESI EVOLUTION SPHERE, without dismantling the existing software structure. The System is structured on the basis of “Pay per use” in a way that each company only incurs the costs of what they actually use.