The deciding factor should be the type and intensity of the past activity and how soon the next session will be. In the instance where you had a hard training session and will most likely have another within 48 hours, it is advisable to drink a sports drink within the first 60 minutes after a strenuous session. If you did only some mild to light exercises, there is no need to.
There is some research that indicates if you consume a sports drink containing protein after physical activity it assist in the muscle recovery process. Some sports drinks are referred to as recovery sports drinks and ordinarily contain both carbohydrates and protein.