Short answer. Yes. When you lend something without specifying a term or a purpose, the arrangement is called a precarium under the Civil Code, and the lender may demand the thing back at will. You do not need a specific reason, and the borrower has no right to insist on keeping it longer.
What the law says
The bailor may demand the thing at will, and the contractual relation is called a precarium, in the following cases: (1) If neither the duration of the contract nor the use to which the thing loaned should be devoted, has been stipulated; or (2) If the use of the thing is merely tolerated by the owner.
Civil Code, Article 1947 — Precarium. Read the full provision →
What a precarium is
Article 1947 of the Civil Code gives a specific name to the kind of loan you describe: a precarium. The bailor may demand the thing at will, and the contractual relation is called a precarium in two situations: first, if neither the duration of the loan nor the use to which the thing should be devoted has been stipulated; and second, if the use of the thing is merely tolerated by the owner. Your situation fits the first case precisely — you set no return date and named no specific purpose, so the arrangement is a precarium and you may ask for the laptop back whenever you choose.
Why no term and no stated use triggers this rule
In an ordinary loan for use — called a commodatum — the borrower has the right to use the thing for the agreed period or for the agreed purpose before the lender can demand it back. That right of use is the borrower's protection against an early demand for return. When neither a period nor a purpose is agreed upon, there is nothing to protect: the borrower has no agreed-upon use to complete, and no agreed-upon time to count on. The law responds by removing the lender's obligation to wait. The lender retains the right to take back their property at any moment.
Tolerated use is the second trigger
The second situation that creates a precarium is when the use of the thing is merely tolerated by the owner. This covers arrangements where there was no formal lending at all — the owner simply allowed someone to use the property without objecting. A neighbor who has been mowing a strip of your land, a relative who has been using a room in your house without any lease, or a friend whose car has been parked in your garage without any agreement — each of these is a tolerated use. Because nothing was actually agreed to, the owner can withdraw that tolerance and demand the property back at will, just as in the case of a precarium.
What the borrower can expect
If the arrangement is a precarium, the borrower has no right to insist on continued use. Once the lender demands return, the borrower must return the thing promptly. The lender does not need to give a reason, a notice period, or a replacement. The borrower's only realistic protection against an inconvenient demand for return is to have agreed at the outset on a specific term or a specific purpose — either of those would convert the arrangement from a precarium into an ordinary commodatum with the borrower's right of use protected for the agreed period or purpose. Without that agreement, the lender holds all the power over when the loan ends.