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

The landmark move marks the first time in five decades that Cubans will be able to travel outside their country without a tourist visa or an invitation from a resident in their destination country.

BBC: Cuba lifts travel restrictions