Your new housemates won’t be the only friends you have. Your friends from home will probably come to stay to check out your new life, and the entertainment.
Accommodation courtesy
As a courtesy you should check that it’s OK with everyone if you can have some guests, especially if they won’t be staying in your room and might be crashing on the couch. Definitely get your housemates permission if you intend to let your mates sleep in their room!
Out-staying a welcome
The length of their stay can also be a cause for friction if they start to out-stay their welcome. Staying so long that they appear to become a resident may well cause your housemates to feel animosity – they are paying the bills and rent after all.
More seriously in this instance you could well be in breach of your tenancy agreement, unless your landlord or letting agent have agreed to it.
Remember too that any damage to or in the accommodation caused by your friends will be down to you. They are your liability!