Oracle Performance And Tunning pack licensing

Hello Everyone

I was wondering if anyone knows how the performance and tunning pack license works

I have 5 Standar Edition Databases

3 o them are sharing the same binaries are only instances inside the same box virtualized with OVM

the other two are on separate boxes each

and finally i have one EE licensed for 4 cores.

So my question is do i have to buy 6 performance and tunning packages.

or

Do i have to buy 4 performance and tunning packages since the first 3 share the same binaries and therefore need only 1 license.

or

do i have to buy 5 performance and tunning packages 1 for each SE and then pay the performance and tunning package for my enterprise eddition based upon the number of cores which is four.