Habits for a specific period of time / Completed habits

[DorianHawkmoon]

Sometimes I want to track an habit for just a period of time, not forever.
A silly example would be training for three months (before a special event). So I start training everyday in May, and finish in August with whatever success I have (a score of 91%)

But from there, how to "complete" the habit, so it no longer modify the score?
Also, is it possible for the score calculation to take into account that the time frame is just three months? So if I manage to exercise all days within that period, score would be 100%.

Not sure how it fits with the purpose of this app.