The trial is the full version, it doesn't limit things in any way. Atlas likely limits things as they built their software around the old LLBLGen Pro Lite version which limited things to 8 tables (as it was free). As we killed off the Lite version when we released v5 some years ago, they told people to use the trial version to make changes which is against our EULA (you may not run the generated code from the trial in production).
Our current License has expired in mid-2018
Again, licenses don't expire, the subscription expires but the software is 100% functional, you just don't have access to updates/new versions. With 'our current license' you mean your LLBLGen Pro v5 subscription?
We don't limit things in any way, nor is the excel plugin something we ship/release so that's atlas' code.
A trial license won't cut it: you can't use the code in production, nor is it limited in functionality (only in time).