Since this is labeled as a 'release candidate' , at least by MUMenu, I am providing the following information for those users who are not familiar with the term:
As of this date the version is stated as a "release candidate". What this means is that it is in its final form with major known bugs fixed and the developer wants the world to test it and report any bugs. After a period of test time as determined by the developer and if the developer chooses to fix any reported bugs before final release or defer them to a later version, the product will be released and given a version number. More than likely at that point it will no longer be free and unless the developer has a method of determining who was testing (using) before it was released , current users will then have to pay full price to use it as most often, released candidates, have an expiration time at which time the product will no longer function unless a licensed is purchased.. If the testers (users who use the pre-release) are tracked, then they may be offered the version for free or at a discount.
As of today the developer posts the product on their website that it is free but is asking for donations. As of March 10th it is also given a version number of 1.3.1. So it remains as anyones guess as to if,, when released,, if it will remain free or be a paid App. However the developer has also published the source code which is a reasonably strong indication that it is likely to continue to be free, at least for the time being.