If you haven't received the most recent issue of a magazine you subscribe to, or if someone has given you a subscription to a magazine you already receive, write to the magazine's subscription department.
If you're moving, notify every magazine you subscribe to at least 4 weeks in advance. Most have a change-of-address form in the publication which you can use, or send the address label from a recent issue.
An annual subscription to a favourite magazine makes an excellent birthday or Christmas present, especially for an elderly relative.