What determines the number of lines stored in replication history?

We are experiencing some replication issues with one database and has been monitoring it closely. One of the observation made is that the number of lines stored in the replication history is lesser than others. for example in this database we have 16 lines dating to 3 days ago. In another database we had 24 lines dating all the way back to the beginning of the year.

I suspect, the number of lines is determined by the amount of data being held by the replication history however, I cannot find any documentation that supports this.

Can anyone shed some light on this?