You can configure BitTorrent to seed/download a certain amount of data over a determined period of time (Transfer Cap) and then automatically stop the upload/download operation, once the above mentioned criteria are met.
To set a transfer cap:
Click on the Options menu > Preferences > Transfer Cap.
Check "Enable Transfer Cap" and set your parameters/limitations:
Transfer Cap: the amount of data to be uploaded/downloaded.
Time period: Number of days.
Limit Type: the type of operation to be performed (download, upload or both).