Yes — WhatsApp and Instagram DM are the most common ways to reserve a spot at a Montenegro beach bar or club. Many bars, particularly around Budva, Przno, and the Lustica Peninsula, manage their reservations entirely through these channels rather than a website form or phone line.
To book, search for the bar on Instagram, find their contact number or DM them directly, and specify your date, number of people, and whether you want loungers or a baldahin cabana. Reply times vary; message a few days ahead in peak season and follow up if you don't hear back within 24 hours. Confirming the cancellation or no-show policy upfront is also a good habit.