How Does Switching Subs Work?

If i buy master package 7 day, could i switch it to say csgo or battlefield 4?
And if i bought battlefield 4, could i switch it to csgo if i didnt like it?
(not buying both, just questions, and i wouldnt be talking about switching them once a week, i mean switching them once, and never again.)

One time within first day

Ok, thanks! and you mean first 24 hours right? not only first day as in 9:34pm to 12:am? this sounds stupid -_-

first 24 hours yes.