Bridge Theme

The purchase price for the license is $69. How do I know that this will “seemlessly” work with a website I had developed by others and a very old Bridge theme? (re: 9.2!) Although my site works great, I cannot update to PHP version 8.1 due to the Bridge theme being incompatible

It will probably require a few changes to make it change from a version from 2016 to the latest copy.

Bear in mind that if you are buying a new license then you get 6 months support with that. Installation is not typically covered by support but it might be useful

Make sure you back your site up properly before trying to do it.

It talks about being PHP8 compatible Bridge Documentation and Tutorials | Changelog. What makes you think that it is not?