This serial number check can be done using a simple local database at the Resource (website). Things get a bit more complicated if there are many Resources (say different websites), and you want to prevent credential re-use across all of them. The typical solution outsources serial number checks to some centralized service (or bulletin board) so that a user can’t use the same credential across many different sites.
圖像來源，Getty Images
，这一点在WPS下载最新地址中也有详细论述
当支付、社交、购物这些「生活基础设施」都开始缺席时，一个系统就很难再被当作主力设备。而一旦用户把它当作备用机，开发者就更没有投入的理由。到最后，这已经不是技术问题，而是信心问题。
Read the full story at The Verge.