3. Intangible assets, net

Intangible assets other than goodwill consist of the following:

(In thousands)	Amortization period	September 30, 2017			December 31, 2016
Gross amount:
Software developed for internal use	3-10 years		17,945			11,438
Acquired proprietary technology	5 years		11,381			13,532
Customer relationships	7-10 years		34,986			34,986
Trade names	20 years		16,357			18,057
Domain names	20 years		199			191
Databases	5-10 years		31,292			31,292
Non-competition agreements	2-5 years		1,768			1,768
			113,928			111,264
Accumulated amortization:
Software developed for internal use			(1,312	)		(505	)
Acquired proprietary technology			(4,124	)		(2,660	)
Customer relationships			(8,431	)		(4,840	)
Trade names			(1,482	)		(916	)
Domain names			(17	)		(10	)
Databases			(6,061	)		(3,354	)
Non-competition agreements			(947	)		(448	)
			(22,374	)		(12,733	)
Net intangible assets:
Software developed for internal use			16,633			10,933
Acquired proprietary technology			7,257			10,872
Customer relationships			26,555			30,146
Trade names			14,875			17,141
Domain names			182			181
Databases			25,231			27,938
Non-competition agreements			821			1,320
		$	91,554		$	98,531

The gross amount associated with software developed for internal use mainly represents capitalized costs of internally developed software. The amounts relating to acquired proprietary technology, customer relationships, trade names, domain names, databases, and non-competition agreements mainly represent the fair values of intangible assets acquired as a result of the acquisition of Fluent, LLC (“Fluent”) effective on December 8, 2015 (the “Fluent Acquisition”) and the acquisition of Q Interactive, LLC (“Q Interactive”) effective on June 8, 2016 (the “Q Interactive Acquisition”).

On January 18, 2017, the Company’s management and Board of Directors approved a plan to merge and fully integrate Q Interactive’s business into Fluent (the “Q Interactive Integration”). As a result, the remaining balance of long-lived assets of $3,626, relating primarily to the acquired proprietary technology and trade names acquired in the Q Interactive Acquisition, was written off to operating expenses as a write-off of long-lived assets.

Amortization expenses of $3,362 and $3,333 for the three months ended September 30, 2017 and 2016, respectively, and $9,931 and $8,726 for the nine months ended September 30, 2017 and 2016, respectively, were included in depreciation and amortization expenses. As of September 30, 2017, intangible assets of $3,444, included in the gross amounts of software developed for internal use, have not been amortized. These intangible assets will start to amortize when they are put into use.

As of September 30, 2017, estimated amortization expenses related to the Company’s intangible assets for the remainder of 2017 through 2022 and thereafter are as follows:

(In thousands)
Year	September 30, 2017
Remainder of 2017	$	3,640
2018		14,307
2019		14,042
2020		13,387
2021		10,204
2022 and thereafter		35,974
Total	$	91,554