Does the electron retain the energy forever ?

Does the electron retain the energy at excited state forever ?

How does the energy flow here ?

The energy of an electron in the first energy level of H atom is -13.6 eV. The possible energy value (s) of the excited state (s) for the electron in He^(+) is (are)

The energy of the electron in the hydrogen atom depends on

When electrons move to a high energy level they:

The energy of the electron in the hydrogen atom is given by the expression

What happens when an electron gains energy ?