Short answer. Yes, if your neighbour benefited or you prevented an imminent loss. Article 2150 makes the owner liable for obligations you incurred in their interest and requires reimbursement of your necessary and useful expenses and any damages you suffered, even without express approval of what you did.
What the law says
Although the officious management may not have been expressly ratified, the owner of the property or business who enjoys the advantages of the same shall be liable for obligations incurred in his interest, and shall reimburse the officious manager for the necessary and useful expenses and for the damages which the latter may have suffered in the performance of his duties.
Civil Code, Article 2150 — Owner's Liability Despite No Ratification. Read the full provision →
What the law says
The same obligation shall be incumbent upon him when the management had for its purpose the prevention of an imminent and manifest loss, although no benefit may have been derived.
Civil Code, Article 2150 — Owner's Liability Despite No Ratification. Read the full provision →
You do not need the owner's prior approval
What you describe — stepping in to run someone else's business while they were away, without being asked — is what the law calls officious management. Article 2150 does not require that the owner approve your actions beforehand, or even ratify them afterward, for you to be entitled to reimbursement. It says plainly that "although the officious management may not have been expressly ratified," the owner can still end up liable to you, as long as the owner actually benefited from what you did, or as long as your intervention prevented a serious loss.
What the owner has to pay you back
Where the owner enjoyed the advantage of your management, Article 2150 makes the owner "liable for obligations incurred in his interest" and requires that the owner "reimburse the officious manager for the necessary and useful expenses and for the damages which the latter may have suffered in the performance of his duties." That covers costs genuinely needed to keep the business running, expenditures that usefully improved or preserved it, and any losses you personally incurred while managing it — not simply your time or a fee for your effort.
Even without a clear benefit, preventing a loss is enough
You do not always have to prove the owner ended up better off. The same article extends the same obligation to reimburse "when the management had for its purpose the prevention of an imminent and manifest loss, although no benefit may have been derived." So if your intervention was aimed at stopping the business from collapsing or suffering serious harm — even if it ultimately did not fully succeed or produce a visible gain — you can still recover your necessary and useful expenses on that basis alone.
Keep records to support your claim
Because reimbursement depends on showing what you spent and why it was necessary or useful, keep receipts, records of payments made on the business's behalf, and any notes explaining the situation you were responding to when you decided to intervene. Being able to show that a real and imminent loss was threatening the business, or that the owner in fact benefited from your management, will make it much easier to establish your right to reimbursement if the owner later disputes the amount you are claiming.