Unlimited.
When you first subscribe to AdRazor we will use the Amazon Advertising API to download your current data. At the time of writing this (August 2021) Amazon makes your last 2 months of data available via the Amazon Advertising API so, for example, if you subscribe on 1st August we will be able to store your data back to the preceding 2nd June.
From then onwards we will update your account with your most current Amazon Advertising data on a daily basis.
So the power of your account... and the insights that you can get from your history... grow each and every day.