When used from the Bag on a Pokémon, raises the PP of a selected move by 1/5 of the move's base PP, until 3 PP Ups or one PP Max have been used on the Pokémon's move. It cannot be used on Sketch.
The amount of PP you can raise any move by is fixed. If you try to use a PP Up in a different game on the same Pokemon, the game will detect that no more PP Ups can be used.
However, since the move you referenced currently has 7 PP, it must be a move that started out with 5 PP, and therefore could use 1 more PP Up to max out at 8 PP. :P
Hope I Helped!