I might be wrong, but I think you cannot combine these.
If you first get the regular supporter upgrade for $12, then you will be billed $12 per year, unless you stop it, or you change to the permanent upgrade, after which you only pay once, and then will not anymore be billed yearly.
The other way around is not possible, you cannot get the permanent upgrade, and afterwards the yearly, so there is no option to have both at the same time.