If the blog/cms was activated on its current domain and the "license mismatch" error appeared right away after the activation, your server may have difficulties with creating "sessions".
This is a case when the blog cannot hold and store the activation, because of an issue with the sessions on the server. Your hosting provider might have set the server up in a way that it needs a specific path for the sessions to be indicated in the PHP script. Usually this is not required, and php sessions work without problems on most hosts without indicating a particular path.
We will first try with the most common path ("/tmp"), and if it didn't work, please contact your hosting provider and ask if the "php session path" is account specific and if you need to use a particular one for your account.
1) Solution with the common path
The muse_blog_main.php file is prepared for this edit. Please open the file in any (non rich-) text editor and remove the two slashes before the 8th line which begins with "define". (On windows they may appear all on one line) After removing those two slashes simply upload it to your server and replace the old file which is stored in the "assets" directory.
Now your blog/cms should be able to keep the license after activating. So you just need to reset and re-activate it. The resetting is by removing the following files via FTP or the file manager of your server. These files can be found in the main directory of your server where all other html files of your website are:
muse_blog_db.sqlite (exists only if you chose "SQLite" as a database)
Then if you refresh the page in the browser, the initial setup wizard should appear and you can activate the blog again.
In case you would like to re-upload the blog anytime on this particular server, please note that you need to use the edited muse_blog_main.php file instead of the original one.
2) Server requires an individual path
If the above solution didn't work, chances are that your server's required session path is not the default one that we tried. In that case you will need to ask your hosting provider for the specific "PHP Session Path" for your particular hosting account. Then you can paste your individual path, which they give you, into the edited PHP file, instead of "/tmp" (on the line, from which we removed the two slashes earlier).