She wanted to go and see him, but how could she go to the house without an invitation?

她想去看看他，但她怎么能不请自来就去他家呢？

youdao

I hated to barge in without an invitation.

我讨厌不经邀请，擅自闯入。

youdao

Woman: I'm sorry. Not without an invitation.

女人：对不起。没有请柬不行。

youdao

Giovanni apologized for coming into the garden without an invitation.

VOA: special.2009.05.30

To attract more users, lowering age limit and allowing log-on without an invitation.

FORBES: Magazine Article

They happen without warning and without an invitation.

FORBES: You Just Missed A Huge Bull Market

Pakistan's former Prime Minister Nawaz Sharif, in an interview with an Indian TV network on the day of elections that returned him to power, said he would love to visit India if invited and then, with a disarming chuckle, added that he would go even without an invitation.

WSJ: Pakistan's Newly Elected Leader Seeks Better India Ties