Yes, if Beoplay E8 Motion are not paired, out of Bluetooth range or no music is streaming for 15 minutes or more, they will automatically switch off to conserve power. If the earbuds are left outside the charging case, the left earbud will remain switched on and eventually lose its battery charge completely, while the right earbud switches off after 15 minutes.
To prevent the battery from draining completely, just make sure that both earbuds are stored in the charged charging case when not in use. If the charging case does not have any battery charge, it will drain the battery of the left earbud.
