Basil lookalike that tastes like aniseed. I bought a herb on the market, thinking it was fresh basil. What I know for sure now, is that this isn't basil. It has a taste that reminds me of anise and fennel. It stays a bit firmer than basil when put on spaghetti. What did I buy?
You bought thai basil. It's used a lot in south east Asia, and an anise-like taste is one of its qualities. 

I don't use it often, but I always have some in stock in the freezer, for some thai or Vietnamese curries or soups.