I bet your Mylog has been running for a good number of years Aerotower and as such will have recorded every detail of each aircraft that has been picked up by you over that time. It holds a lot of info not just about the aircraft but also when you saw it, its flight ID, route, start and finish altitudes etc, etc
It may be a good idea to delete the old data now and again through MyLog Tools and maybe even the photos there.
Alan