Some advantages of this over the various apps I've tried:
* Free
* No ads
* Synchronised web + mobile apps
* No demoralising penalties for breaking a streak
* At a glance you can see both recent usage (which is most relevant) and long term usage (which is really motivating)
A conditional formatting either gradient colors the squares, or colors them good or bad colors.
Columns after 31 keep count of each value in this month.
Some summary tables use sumproduct to pull some trends.