Ruling on end of menstruation is once bleeding has ceased, the woman should perform ghusl and commence prayers.
So in the case mentioned at the end of 7 days when bleeding stops she would perform ghusl and pray however if bleeding was to reoccur after a day or she would stop salaah and see what happens as it is still within the maximum 10 days.
Now if it ends within the maximum 10 days end she will perform ghusl once again and if it exceeds 10 days then she would perform ghusl after the 10 days end and commence salaah as it cannot be menstruation after 10 days.
If this is still unclear please post again