The travellers need a visa to go to Laos. The validity period of the passport must be at least 6 months longer than the time of stay in Laos. Tourist visas are valid for one entry for a stay of 30 days. They can be renewed. You can contact the Vientiane Immigration Office to renew your visa for a sum of USD 2 per day. A penalty of USD 10 per day will be applied if the validity of the visa is exceeded.
You can get your visa upon arrival at the airport or at the border gates. You should prepare your valid passport, an ID photo and 35 usd in cash. You will have your 1 month visa after a few minutes without formalities. If you don't have a photo with you, don't worry, you will have your photo taken on spot  with 1 usd.