When your friend opens the song file he/she will get a notification about missing Rack Extensions, and will be presented with two options: - "View in Web Shop". This links to the relevant Rack Extensions in the Reason Studios Shop, where he/she can choose to try it for 30 days or purchase right away. - "OK". This opens the song without the Rack Extension. In any case, the song can still be opened normally and any Rack Extensions they don't own will be replaced by a placeholder that can redirect you to the Reason Studios Shop to try or purchase the Rack Extension.