The Nike+ SportWatch memory can store approximately 15 hours of run data.
Each time you connect your SportWatch to a computer with Nike+ Connect installed, the software will automatically launch, uploading your runs to Nike+ and removing them from the watch's memory. You should connect your watch to your computer regularly to prevent your watch's memory from becoming full. If your memory does become full, connect your watch to your computer as soon as possible to upload your runs and free up your watch's memory to record more runs.
Note: Runs cannot be deleted from the watch. Once they are uploaded, they will be removed from the SportWatch's memory to make space for new runs. However, the run summaries of your most recent runs will remain viewable in your History section, even though the source data has been uploaded and removed from the watch's memory.