Look at Spotify for how freemium works

Freemium basically implies you can use 80% of the product but some juicy functionality is in the other 20%.

For example:

An image to pdf generator, but it can also do OCR. The free product has lasting value, but the premium option adds to it.

A trail is free but not freemium since it has no lasting impact.

I would instead use wording like: - try it - try now - try it now

This still works as an call to action but does not decieve the user