I'm guessing this was bought in the veggie section of a supermarket rather than a garden centre? If so you've done well to keep it 8 months indoors. What you have there is a pot crammed full of separate plants designed for a quick sale and a short life as a cooking ingredient rather than a long term house plant. Basically it needs masses more light. And check for aphids. They love indoor basil.

As I said 8 months is a good innings and I'd just go and buy another one if it were mine.

I agree with Flora. Unless you can take a few cuttings and root them in water. You will need to have at least a set of nodes under the water to produce roots. Put it in a small vase of water in a bright window. I have good luck rooting basil.

Thank you both. I will try rooting them as I don't have anything to lose anyway. :) I already took some cuttings and put them in water by the window.

cut the stem and harvest the bunch of leaves at the top from time to time, rather than always plucking the larger leaves toward the bottom every time you harvest - cutting the top encourages new growth on lower nodes of the plant - i like to use the lighter-colored, small leaves on top as fresh basil to top dishes - the older leaves are better for actual cooking

i mean, you may have to start over with the plant as is now - but to keep a new plant productive for a longer time, I recommend the above strategy - also, it's worth noting that basil is an annual, meaning it lives only a season, produces seeds that will become plants for the next season, and then dies - 8 months being productive indoors ain't bad - but, to get the most out of one year, follow that advice - and cut the seeds of as they mature unless you want to harvest them - stopping seed development redirects energy toward forming leaves