When you cancel your subscription, you can still access and use your account (and all the feature associated with it) until the end of your free trial or paid subscription period. At the end your free trial or paid subscription period, you will still be able to log into and access your account, but you will not be able to access or use any of the paid features.
TweetReports will save data from your searches, reports, etc. for up to two weeks after your subscription period has ended. After two weeks, the data is deleted from the database. If you re-subscribe within the two weeks, you should not lose any data.