Enshrouded 1.0: Old Saves Work, Cross-Play Must Wait
Enshrouded 1.0 keeps Early Access saves and does not require a second PC purchase. Cross-platform multiplayer will not be available at launch.
Enshrouded 1.0 will accept your Early Access saves, and existing PC owners do not need to buy the game again. Keen Games confirmed both points in its October 13 launch FAQ ahead of the October 15 release.
Cross-platform multiplayer is the important exception. It will not be available at launch. The studio is working on it, but has no estimate for when it will arrive. If your group plans to split between platforms, do not buy on the assumption that 1.0 lets everyone join the same session.
Keeping a save is allowed; restarting is optional
Existing save files will be converted into a new, more efficient format. Keen encourages players to start again because it has improved the world and the opening hours, but that is a recommendation rather than a compulsory wipe.
That leaves the choice with you. Continue the world you have already built, or begin a fresh run to see the revised introduction. The ownership confirmation applies to the PC Early Access copy; it is not a promise of a free license on another platform.
The FAQ does not confirm cross-save. Save compatibility on PC and playing across platforms are separate questions, and neither answer should be stretched into an account-transfer guarantee.

What to check before your first 1.0 session
Keen plans to publish the full changelog on October 14, a day before release. A trailer is scheduled for the same day, followed by a highlights video on launch day. Those are upcoming releases, not material already available when this FAQ was posted.
Early Access owners also receive three decorative base props. Claim them through Redeem Add-Ons in the escape menu. An eligible player can redeem them repeatedly and place copies in a later buyer's world. The later buyer can remove those props, but cannot place them independently.
Those decorations are a small bonus, not the reason to rush a purchase. The useful launch checks are whether your group shares a supported platform and whether you want to continue an existing world.
Our Sparkworks breakdown covers the new building logic system, while the Steam page provides the PC purchase destination. Read the final changelog before planning around unconfirmed launch features. Keep your save if you want it; wait for a dated cross-platform announcement before buying specifically for a mixed-platform group.