In order to get the Tissot 2 Year Guarantee or in my case the international warranty you need to buy it from an Authorized dealer. As long as you get a little wallet sized card with the date of purchase, reference number, stamp of dealer and serial # your all good. Now I don’t know if you get a watch from amazon or the dealer on ebay, if it comes with this stuff. So before you buy online you should make sure all this stuff is available to you
I would also recommend checking out Tissot’s website for information on the warranty and also they have a FAQ on the list of Tissot watches including all the ISO standards built in to the watch.