Unajua tusidanganyane hapa!!! The thing is, for the satellite to generate energy for whatever purpose including the little energy used in its locomotion, it is attached with solar panels. The panels charge the battery attached with the satellite, something that enable the satellite to fulfill its purpose, communication in particular. The reason why it is attached in the orbit is clear, that it can have the equivalent rotation with the earth. That is why a satellite use to record information of a specific location. For example, a satellite that provides information about Africa will remain providing such information alone, it will never be over Europe - it goes perpendicular with the earth. So a satellite is not in the orbit for easy locomotion, but for equivalency.
About maintenance, that is dependent, some are picked back to earth and some are destroyed. The same way used to put them there is the same way used to pick them back. Remember, they are put there by rockets. See the image, note the solar peddles,
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I think it is enough