I'll chip in here with some information on how magazine subscriptions, and many magazine subscriptions work. Stereophile, like nearly all magazines, if not all, use a subscription service to sell subscriptions. Stereophile uses the same one that the vast majority of other magazines use.
Nearly all magazines, if not all, also don't print or mail their magazines. They use a service to do that. Magazines write, compose, and publish. There's nothing new about that. The New York Times and USA Today, among other newspapers, also don't print, distribute, or sell subscriptions to their newspapers. They use services to do that. There is one local to me that prints and distributes USA Today in this part of the country.
When you buy a subscription to USA Today you don't buy it from USA Today, you buy it from the subscription service that they hired to sell subscriptions. It's the same deal as with Stereophile and nearly every other magazine.
Stereophile doesn't give away the ear buds. Road & Track doesn't give away the tire gauge. The subscription services that they hired to sell subscriptions give those away. And in the case of Stereophile, for a subscription that costs less than $1.00 an issue, I think it's silly to believe that any gift would be of even decent quality.
Stereophile, and other magazines, are looking to pay for the printing and distribution of their magazines with their cut of the subscription. They want to do the same thing with the jobbers who they have hired to put their magazines on magazine racks. There is no profit in subscriptions to magazines and newspapers for the magazine and newspaper owners. The printers, mailers, jobbers, and subscription services make the profit on the physical magazines and newspapers.
Magazines and newspapers make their profit on the advertising they sell. It's been that way for a couple of centuries now.
On the subject of subscriptions, you can work backwards from the last issue date and figure out roughly when you need to have a renewal in. In the case of Stereophile, if you last issue is October, you typically receive that issue around the beginning or September at the latest. That's because the October issue is printed in mid-August and distribution begins the third week of August.
The final draft of the magazine goes to the printer at the beginning of August, and the subscription service sends the current subscription list to the mailing service the last week in July. These subscription services are usually pretty slow in getting changes made. My personal experience is that it can take them two months to get their mailing lists updated after you send in a subscription payment. If that were to happen in this example, you would need to have your subscription renewal in around the end of May or risk missing an issue. And this is why some services err on the side of caution and continue having the magazine mailed after a subscription renewal is past due. But I've found that you can't count on having that happen.
Happy listening.