Oliver used 1/3 x 135 = <<1/3*135=45>>45 stickers.
So, there were 135 - 45 = <<135-45=90>>90 stickers remaining.
His friend received 2/5 x 90 = <<2/5*90=36>>36 stickers.
Therefore, Oliver kept 90 - 36 = <<90-36=54>>54 stickers.
#### 54