When you are implementing any Dynamics 365 production, you will need an implementation partner to help you with your digital transformation journey. Dynamics 365 implementation partners bring a lot of expertise in the area so you can be assured of successful implementation. Here are the two main reasons you would need an implementation partner:

• Product licenses: As a customer, you cannot directly buy the licenses from Microsoft. Microsoft has partnered with many companies that work in the Dynamics 365 domain and sell the Dynamics 365 product licenses to customers through these partners.
• Partner's expertise: To become a partner with Microsoft, companies have to prove to Microsoft that they have the expertise to implement the Dynamics 365 products. Partners are the first layer of support to the customer. Microsoft relies on the partner's expertise to help customers with the implementation and support.