This is a card that allows you to visit with free entrance lots of museums of the Piedmont region in Italy all year round. There is a similar card for Lombardy. I have read the information on the website of Abbonamento Musei Torino Piemonte and I haven't found any reference to the fact that this card is only for Italians or only for Italy residents. Nevertheless, I have the suspicion that, as a stranger non-resident in Italy, I cannot buy such a card online since an address from Italy seems to be required by the application form to register. But, what about buying it at one of the points of sale at Turin? I have tried to ask this through this information form, but I haven't received any anwser.
Finally, I have received an answer from Associazione Abbonamento Musei of Turin. As a non-resident, one cannot buy this card online because they cannot send it outside Italy. Nevertheless, it is possible to buy it without any problem at one of the points of sale at Turin, for instance the one which is situated at Piazza Castello in the corner with via Garibaldi. They will give you the card at that moment and you will able to use it immediately.
Now I've been at Piedmont, I've used this card lots of times and it has been really useful. Even in the very few museums that are not in the list of free museums (for instance, Castello della Manta, which is really impressive) I've discovered that you can often get a discount with the card. Anyway, keep in mind that, once you get the card, it's important that you bring your receipt with you because they will sometimes request it to you.