Complex sentence: This may include factory acceptance testing, i.e. the testing done by factory users before the product or system is moved to its destination site, after which site acceptance testing may be performed by the users at the site.
Split into simpler sentences: This may include factory acceptance testing, i.e. the testing done by factory users before the product or system is moved to its destination site. Even after it, site acceptance testing may be performed by the users at the site.