Advertisers plugin

This will allow websites with loads of events to sprinkle adverts throughout their calendar

with different options

appear at top

appear mid way

appear at the bottom

so imagine main calendar with 15 events that month

right at the top could be an advert for say cars

midway down is an advert for shopping  it could be adwords advert from google

right at the end is some other advert

connected to woocomerce- you buy a spot on a calendar