You Do Need power plug adapter while traveling from Serbia to Laos.

Here is Why You Need An Adapter

The outlet and plug type used in Laos are A, B, C, E and F and in Serbia are C and F. This is how they look like.

Serbia

In Serbia, outlets of type C and F are in use.

Type C

Type F

Laos

In Laos, outlets of type A, B, C, E and F are in use.

Type A

Type B

Type C

Type E

Type F