SiteLock will alert you if your site is vulnerable to any of these issues, as well as if your site gets blacklisted for any reason by search engines or spam monitoring tools. In addition to all of this, SiteLock also provides a trust seal which is a small image placed on sites that are secure.
SiteLocks need to be bought per domain. So incase of a multi domain hosting package or a reseller hosting package, SiteLock will need to be bought for each add-on domain. Also the minimum time provided for a SiteLock order is 1 year and the order will be active for a year from the date of purchase. When SiteLock is purchased, it starts scanning the website automatically, using scans like Malware scans, Spam scans, etc.