Sorry for my misunderstanding from my previous reply Pavvel
There is no setting to limit this permalink at this point of time.
But you can limit the permalink length by customize in the file:
.../components/com_easyblog/themes/wireframe/composer/manager.php
on the line 142 add
maxlength="<your prefer value" as example:
http://take.ms/IUAKO
You also can do template override for this file so that it will not override once you update your EasyBlog
You are suggest to backup the file that you want to customize just for precaution step