Expiration License or Use as demand

I’m wondering if it is an one time License Buy ($159 USD) with Extended Download in case of damage or reinstallation, or i need to pay every year to use the extensión…??

With the purchase of a license you have the right to receive free updates for one year. After that, your license will continue to function indefinitely on the versions of SketchUp released up to that point. If you want to use the extension on SketchUp versions released more than one year after your purchase, you’ll have to upgrade the license.