Upgrading Commerce 1 to Commerce 2
You can not run Commerce 1 on Craft 3.

Commerce was completely re-written for Craft 3 compatibility.  Indeed the final release of Commerce 2 actually requires Craft 3.1.

That said, your license for Commerce 1 should work for Commerce 2 once you have that installed but note there is a lot more to upgrading sites to Craft 3/Commerce 2 than just installing the new versions - there are extensive changes needed to both - including template and fundamental changes to custom plugins if you have written any of those.

See:


https://docs.craftcms.com/v3/upgrade.html
https://docs.craftcms.com/commerce/v2/changes-in-commerce-2.html