To find the unit rate of beads per bracelet, you divide the total number of beads by the number of friends (bracelets):
\[ \text{Unit Rate} = \frac{\text{Total Beads}}{\text{Number of Friends}} = \frac{156 \text{ beads}}{12 \text{ friends}} = 13 \text{ beads per bracelet} \]
So, the unit rate is 13 beads.