In order to comply with YouTube's terms of services, we would like to explain below how we process, store and display data gathered from YouTube in quintly.
Public YouTube data cannot be stored for longer than 30 days
You'll be able to access the past 30 days of historic data on profile level for the channels you are tracking and don't have admin rights to. If you are tracking channels that are connected to YouTube Analytics, you'll be able to access the data as before. You’ll also be able to access interactions (e.g. videos) data as before both on the public and private level.
For further reference, you can read YouTube's terms of services.