title: Google Script for Spreadsheet : How to keep value saved for "ever"?
body: <p>I'm building a Google Script for my Spreadsheets, and the script queries an external API that requires payment every time it is queried.</p>
  
  <p>I'd like my script to keep in memory the value if it has been already loaded (meaning if I didn't changed the other cells used by this script), in order to avoid querying the API every time I load the page.</p>
  
  <p>I thought about using the Cache, especially the <code>CacheService.getDocumentCache()</code>, but it's not a long term storage.</p>
  
  <p>Is there a better alternative ?</p>