Thanks for reaching out!
Yes, the price is one time payment for the template license.
Yes, it is possible to use template for an unlimited number of applications.
More info about version control, you could read here:
More about marketplace policies, you can read here:
Please note, that there are different types of licenses for templates usage. Be sure to read about them in the link above.
- Standard Template License.
- Developer Template License.
Also you could read about the Bubble pricing policies here:
Hope this helps