There are many different situations in which your SkyComputer may get deleted making you lose your data:
Free Plan: You will lose your SkyComputer if no SkyCredits are being consumed within 72 hours.
Pay-as-You-Go: You will lose your SkyComputer if no SkyCredits are being consumed within 7 days.
Monthly Subscription: Your SkyComputer will NOT be deleted as long as you have an active subscription. You do not need to keep logging in to your SkyComputer to prevent the deletion. However, cancelling your subscription will cause a downgrade to Pay-as-You-Go when your plan expires and is not renewed. That will cause your SkyComputer deletion as there is less SkyStorage on Pay-as-You-Go compared to what you had when your subscription was active.
If you miss your payment and you get downgraded to Pay-as-You-Go as well and you will also lose your SkyComputer and all your data.
You will also have to delete your SkyComputer before you can connect to a different data center.
Upgrading to a plan that comes with more SkyStorage does not make you lose your SkyComputer. However, when your SkyStorage has to be decreased we need to delete your SkyComputer and you will have to start fresh.