Professional services are offered by many SaaS companies to help customers implement, customize, and manage software so the customer receives the maximum value from their investment Examples of common professional services include the upfront implementation of the software, integration with internal/external systems, and custom development of extended features. Professional services engagements can be short-term, one-time projects or longer-term, retainer-style engagements. They can be billed on a fixed fee, cost-plus, or time and materials basis.