If they click your link (that includes the `?cid` parameter) while they're on your website, I believe the `cid` value is cookied/stored with their Microsoft Sto

If they click your link (that includes the `?cid` parameter) while they're on your website, I believe the `cid` value is cookied/stored with their Microsoft Store profile, and will be respected even if they buy later directly from the Store. If they visit your website but don't click the link, then there's no way for the Store to attribute the sale to your website, so you'll probably be charged full freight (15%).