<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-09-04</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001102993</issuerCik>
        <issuerName>LIVEPERSON INC</issuerName>
        <issuerTradingSymbol>LPSN</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001882368</rptOwnerCik>
            <rptOwnerName>Tjon Karin-Joyce</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O LIVEPERSON, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>530 7TH AVE, FLOOR M1</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10018</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>18666</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On September 4, 2026, pursuant to the terms of the Amended and Restated Merger Agreement, dated as of July 2, 2026 (the &quot;Merger Agreement&quot;), by and among the Issuer, SoundHound AI, Inc., a Delaware corporation (the &quot;Parent&quot;), Lightspeed Merger Sub Inc., a Delaware corporation and an indirect wholly owned subsidiary of Parent (&quot;Merger Sub&quot;), and Lightspeed Merger Sub II Inc., a Delaware corporation and an indirect wholly owned subsidiary of Parent (&quot;Merger Sub II&quot;), Merger Sub merged with and into the Issuer and immediately thereafter, Merger Sub II merged with and into the Issuer, with the Issuer continuing as the surviving corporation as an indirect wholly owned subsidiary of Parent (the &quot;Mergers&quot;).</footnote>
        <footnote id="F2">In connection with the Mergers, each share of Issuer common stock was cancelled and converted into the right to receive 0.4673 fully paid and nonassessable shares of Parent's Class A common stock (the &quot;Per Share Merger Consideration&quot;), subject to the terms and conditions of the Merger Agreement.</footnote>
        <footnote id="F3">This number reflects the Issuer's 1-for-15 reverse stock split effected October 13, 2025.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Monica L. Greenberg, Attorney-in-Fact for Karin-Joyce Tjon</signatureName>
        <signatureDate>2026-09-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
