What happens when I reach my goal total / end date?
Using the commitment dial, you can set a goal total (the amount you want to get to) or goal date (the date you want the goal to finish). This is useful when you want the goal to stop at a certain point, e.g. once you've read the last page in a book, or on the day all your exams are finished for a studying goal.
The way Beeminder handles this depends on how exactly you've set up your goal.
What if I reached my end date?
When you reach the end date, your goal will go into the "success" state, and offer you the option to archive or restart your goal. Restarting works pretty much like restarting an archived goal. There's no akrasia horizon on archiving or restarting your goal when it's in the "success" state!
What about if I've reached my goal total?
Once you've reached your goal total, your goal may continue until the goal date or implied goal date. For example, if you said you want to get to a total of 100 by 20th May, then the goal will continue until 20th May even if you've already hit 100... but it won't require more data. Once it reaches that end date, it'll go into the success state as mentioned above.
If you have your goal set up by goal rate and goal total, there's still an implied goal date as well. If you said you want to reach 100 in total at a rate of +10 per day, then your goal will go into the success state after 10 days -- even if you get to 100 after 5 days. Again, it won't require more data, it just won't go into the success state until the implied end date is reached.
Keywords: changing your goal, setting a goal total, setting an end date