Mich. Comp. Laws § 450.4301: Members; contribution.

Sec. 301.

A contribution of a member to a limited liability company may consist of any tangible or intangible property or benefit to the company, including cash, property, services performed, promissory notes, contracts for services to be performed, or other binding obligation to contribute cash or property or to perform services.

A contribution of an obligation to contribute cash or property or to perform services may be in exchange for a present membership interest or for a future membership interest, including a future profits interest, as provided in an operating agreement.