Absolutely yes, there is no limited function.
You can generate invoice in the email sent after successfully purchase, which included license key.
Tinker 2's payment is processed via Gumroad.
Yes, You can use Tinker 2 on all your computers, but not allowed to share to other people.
Tinker 2 license is for single person.
Using license will help you remove random quote popup when using Tinker 2. And it will support us develop the project, we're appreciate it <3!