nmb
2
You can continue if you are satisfied with the product. But then it depends for what purpose you use the computer - home or business apart, do you use it just for checking mails and reading news? Or what else do you do? Advanced users need the pro and AIS versions as it contains features such as safezone and sandbox. Unless you dont do banking, dont use sandbox while browsing, and you dont want antispam, you are good to go with free version.
But it costs very less for multiple years. Decision is what you have to make 
Try the link given by the program interface itself, as you can get offers which give you more discount.