The Renew button does not appear on their profile if the member's status is Pending - Renewal. This status means that a renewal invoice has been automatically generated by the system or manually generated by the administrator, or that the member has already started the renewal but has not completed the payment.
In the first case, the member should click the renewal option within their renewal email notice to begin the renewal process. In the second case, the member should pay the outstanding membership fee to complete the renewal process.