Pay As You Go sessions have temporary storage which is deleted after your session (all games uninstalled and removed), unless you own a stim subscription. This includes cheaper storage-only subscriptions found on https://stim.io/storage/purchase.
With any Stim Subscription, as long as the subscription remains active, all of your installed programs, games, settings, and files will remain on your Cloud PC after Pay As You Go sessions, which you can migrate and start in any region on planet earth.
With an active performance level subscription, Pay As You Go prices are also 30% lower, making subscriptions a viable addition to Pay As You Go. This discount is not applied if you only own a cheaper storage-only subscription (mentioned above).
By default, Pay As You Go sessions have a 128GB C:/ drive, but you can add an additional 100GB for free by using this trick: https://stimsocial.zendesk.com/hc/en-us/articles/31055839233939-Easter-Egg-Enable-100GB-of-Temp-Storage