The "Cursed" flaw allows for a wide variety of traditional weaknesses to be simulated in Vampire. Under the guidelines for this flaw (VRev, 301), how many points would you give for the inability to enter a building without the invitation or express permission of the owner? Upvotes for "showing your work" — that is, explaining why you believe your version to be correctly priced.
A version of this flaw already exists in one of the sourcebooks. In clanbook Tzimisce on pg. 43 there is a 3-Point flaw named "Privacy Obsession" with two effects:
If you're not interested in having that second effect, but wanted to make it impossible to enter a home uninvited, rather than simply requiring a Willpower check, it would probably be balanced to have that as a 3-Point flaw as well. You're losing one specific hindrance and making one a bit more strict.
Assuming the vampire has to be invited in by someone with the authority to do so (i.e. not houseguests of the residents and certainly not one of the vampire's own cohorts) I'd place it at a 2-point flaw... A bit weaker than "Can't Cross Running Water" and "Repelled by Crosses."
When restricted to dwellings it becomes a powerful but situational weakness. There are times (or entire campaigns) where it can be a true thorn in the vampire's side. But in most cases it will be irrelevant (a lot of play takes place in public and semi-public spaces, such as city streets or Elysium).
It loses a point from the other two "vampiric" drawbacks because it is easily circumventable by many disciplines. Both dominate ("Invite me in." "I will invite you in.") and presence ("Hey buddy, why don't you let me in?") have easy routes around this.
Bump the value of the flaw down to one point if ANYONE inside the building can invite the vampiare inside. Bump it back up to three if the invitation has to be particularly explicit/formal, or if the restrictions are particularly strict (i.e. no breaking into public spaces that are closed, or storage lockers).
Of course, as with any custom merit/flaw, you may want to tilt it a bit if the particular campaign you're in is particularly unusual in some way.