To be able to have Amazon Fresh you must also have Amazon Prime as well.
There's no option to purchase Amazon Fresh without a subscription to Amazon Prime.
If you have Amazon Prime already you can purchase a subscription to Amazon Fresh for $14.99 per month which works out to be a cost of $179.88 per year.
But you can only pay for Amazon fresh per month and not per year.
The cost of Amazon Prime is $119 per year or $12.99 per month and the first 30 days of the annual subscription to Amazon Prime are free, and you can cancel anytime.