This is actually a promotion run by AER LINGUS (Aer Lingus), and the Avios you earn can be combined with your British Airways Avios and used together. Based on previous valuations, 15,000 Avios are worth about $195, so on paper you still come out ahead and get The Economist for free. That said, in the current environment, there is still some risk in acquiring this many miles. Of course, if you already wanted to subscribe to the magazine, this could still be a good option. Just remember to register for an Aer Lingus frequent flyer account first.