Validity period once activated

Hi,

I would like to know the validity period once the pass is activated.
Say I have the 7 days pass and I activate it on the following period:

12 April at 8am for the narita express to Tokyo

Would I be still be able to use it for trips at the following time?

19 April at 7am from Shinjuku station to Narita using the narita express

Or do I need to purchase this separately?

Thanks,
Chee Keng