The Mevo app gives you the option to add a default signature, such as a hashtag, to the end of stream's title.
Open the app's settings by tapping the 'More Options' icon, followed by the gearwheel.
Tap the Live Streaming menu.
Below all the available providers is the Signature option. Tap this to reveal a keyboard and set a signature.
Type in your desired signature.
If you wish for the signature to be a hashtag, be sure to include the hash symbol (#) and no spaces in your signature.
When you go live, that signature will by default be added to the end of your stream title.