I'm going to email for a refund as it appears to be breaking the ToS, 3 months is a bit much!!
How long are products offered in the Buddy Store supported?, or
Will I have to rebuy a product at the next game client expansion?
This concept is called a product's End-of-Life (EOL). The current Developer agreement requires developers to support their products for whichever comes first:
18 months after the product is first published, or
the next game client expansion
To clarify how the "first publication" clause works...
Assume a product is made available, and you purchase the product 12 months later. The developer is only required to support that product for six months more. The "first publication" date is available in the product's change log.
It is up to each developer as to how an EOL due to expansion is handled...
The developer may just 'update' his product and "keep going" with the same product. Alternatively, the developer may shelve the old product, and introduce a new one. Since each expansion usually requires a complete rewrite of many products (Combat Routines in particular), the latter situation is very likely. Thus, you may be faced with re-buying the product when the game client expansion drops.