The library is dual-licensed as AGPL plus a commercial license. So everything is in the open and can be tested and tried out under the AGPL. Once the library is used in a commercial context, you nearly always need to buy the commercial licenses to stay compliant. This is how it generally works.
What the commercial license does is a different thing. You could charge once OR once and for every upgrade to an (arbitrarily defined) new major version OR each year via a subscription OR ... It is really up to you and how you want to handle this.
What the commercial license does is a different thing. You could charge once OR once and for every upgrade to an (arbitrarily defined) new major version OR each year via a subscription OR ... It is really up to you and how you want to handle this.