Answer
It is a CTIA and carrier requirement to include your shop's name in each SMS marketing message.
Not including it could lead to higher unsubscribe rates and spam complaints which, in turn, results in carrier filtering.
Including your shop name at the beginning of each message is considered a best practice (as opposed to including it later in the message). Postscript takes a product-led approach to compliance so all Postscript messages will default to include your shop name at the beginning of each message.
Besides, wouldn't you like to know right away who's texting you?