Intangible assets, net

Intangible assets, net, other than goodwill, consist of the following:

	Amortization period (in years)		September 30, 2019			December 31, 2018
Gross amount:
Software developed for internal use		3	$	4,427		$	3,037
Acquired proprietary technology		4-5		13,559			11,459
Customer relationships		6-10		37,286			34,986
Trade names		4-20		16,657			16,357
Domain names		20		191			191
Databases		5-10		31,292			31,292
Non-competition agreements		2-5		1,768			1,768
Total gross amount				105,180			99,090
Accumulated amortization:
Software developed for internal use				(1,724	)		(1,282	)
Acquired proprietary technology				(8,827	)		(6,987	)
Customer relationships				(18,116	)		(14,417	)
Trade names				(3,124	)		(2,504	)
Domain names				(36	)		(29	)
Databases				(13,280	)		(10,573	)
Non-competition agreements				(1,595	)		(1,486	)
Total accumulated amortization				(46,702	)		(37,278	)
Net intangible assets:
Software developed for internal use				2,703			1,755
Acquired proprietary technology				4,732			4,472
Customer relationships				19,170			20,569
Trade names				13,533			13,853
Domain names				155			162
Databases				18,012			20,719
Non-competition agreements				173			282
Total intangible assets, net			$	58,478		$	61,812

The gross amounts associated with software developed for internal use primarily represent capitalized costs for internally-developed software. The amounts relating to acquired proprietary technology, customer relationships, trade names, domain names, databases and non-competition agreements primarily represent the fair values of intangible assets acquired as a result of the acquisition of Fluent, LLC ("Fluent LLC"), effective on

December 8, 2015 (

the "Fluent LLC Acquisition"),

the acquisition of Q Interactive, LLC, effective on

June 8, 2016 (

the "Q Interactive Acquisition") and the acquisition of substantially all the assets of AdParlor

Holdings, Inc. and certain of its affiliates

, effective

July 1, 2019 (

see

Note

Business Acquisition

During the

three

months ended

September 30, 2019,

the Company determined that its declining operating results constituted a triggering event. As such, the Company conducted an interim test of the recoverability of its long-lived assets. Based on the results of this recoverability test, which measured the Company's projected undiscounted cash flows as compared to the carrying value of the asset group, the Company determined that, as of

September 30, 2019,

its long-lived assets were

not

impaired. The Company believes that the assumptions utilized in this interim impairment testing, including the determination of estimated future cash flows, are reasonable. Future tests

may

indicate impairment if actual future cash flows or other factors differ from the assumptions used in the Company's interim impairment test at

September 30, 2019.

Amortization expense of

$3,456

and

$3,228

for the

three

months ended

September 30, 2019

and

2018

and

$9,708

and

$9,653

for the

nine

months ended

September 30, 2019

and

2018

, respectively, are included in depreciation and amortization expenses in the consolidated statements of operations. As of

September 30, 2019

, intangible assets with a carrying amount of

$398

, included in the gross amount of software developed for internal use, have

not

commenced amortization, as they are

not

ready for their intended use.

As of

September 30, 2019

, estimated amortization expenses related to the Company's intangible assets for the remainder of

2019

through

2024

and thereafter are as follows:

Year	September 30, 2019
Remainder of 2019	$	3,443
2020		13,623
2021		10,810
2022		9,171
2023		4,663
2024 and thereafter		16,768
Total	$	58,478