To believe or agree with a theory or an idea (used with to).
To sign up to have copies of a publication, such as a newspaper or a magazine, delivered for a period of time.
To agree to buy shares in a company.
To pay money to be a member of an organization.
To contribute or promise to contribute money to a common fund.
To indicate interest in the communications made by a person or organization.
To pay for the provision of a service, such as Internet access or a cell phone plan.
To register for notifications about an event or similar.
To sign; to mark with one's signature as a token of consent or attestation.
To promise to give, by writing one's name with the amount.
To agree with what a person says, to be persuaded by their arguments.
To grasp the essential meaning of what a person is saying, to understand a person's argument and point of view.