Keeping accurate notes is essential to homebrewing. It's important to know what you did, how you did it, etc.

I use Beersmith to forumulate my recipes, but I don't use it as my system-of-record as to what was brewed. For that I prefer a bound notebook that I fill out in ink on brew day. I use this notebook to keep track of everything. It has spaces for the recipe, brewing notes, fermentation notes, bottling/packaging notes, tasting notes, and spots for various stats like OG/FG, fermentation temperatures, etc.

Here's an example of the fermentation and bottling notes that I took for an IPA I recently brewed:

Example Notebook Page