Through purchasing aggregator submissions with BrightLocal, your listings are managed and marked with a trusted data stamp for 12 months. This also enables you to continuously update your listing for free within this 12 month period.
The major benefit of renewing your submission to data aggregators is that your data retains this 'trusted' status within aggregator feeds to 3rd party sites. This means that 3rd party sites see this data as being more 'official' and are less likely to overwrite it with data that is crawled/imported from other sources.
If the subscription is not renewed, your data won't get deleted from the 3rd party's sites because they buy it from the aggregators so it's useful to them but you won't be able to update the data on your listing anymore.
It is also worth to point put that local search experts recommend keeping your aggregator listings claimed and trusted.
There is a renewal fee to repurchase your submissions to the aggregators and keep your data trusted. The renewal fee is the same as for the initial submission.