The following table disaggregates the Company’s revenue by geography which provides information as to the major source of revenue (in thousands).

	Three Months Ended
	March 31,
Primary Geographic Markets	2019		2018
North America	$	34,084	$	27,483
International		8,735		3,036
Total	$	42,819	$	30,519

The following table presents the Company’s revenues disaggregated by revenue source (in thousands, unaudited).

	Three Months Ended
	March 31,
	2019		2018
Subscription services	$	39,861	$	28,525
Professional services		2,958		1,994
Total revenues	$	42,819	$	30,519

The Company does not have material amounts of contract assets since revenue is recognized as control of goods is transferred or as services are performed. There are a small number of professional services that may occur over a period of time, but that period of time is generally very short in duration. Any contract assets that may arise are recorded in other assets in the Company’s consolidated balance sheet. As of March 31, 2019, the Company had $0.8 million in unbilled receivables related to services performed which were not billed.

The Company’s contract liabilities consist of advance payments and deferred revenue. The Company’s contract liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. The Company classifies advance payments and deferred revenue as current or noncurrent based on the timing of when it expects to recognize revenue. Generally all contract liabilities are expected to be recognized within one year and are included in deferred revenue in the Company’s consolidated balance sheet. The noncurrent portion of deferred revenue is included and separately disclosed in the Company’s consolidated balance sheet.

Deferred costs, which primarily consist of deferred sales commissions, were $17.4 million and $16.8 million as of March 31, 2019 and December 31, 2018, respectively. For the three months ended March 31, 2019 and 2018, amortization expense for the deferred costs was $1.6 million and $1.2 million, respectively, and there was no impairment loss in relation to the costs capitalized.

$31.7 million and $24.5 million of subscription services revenue was recognized during the three months ended March 31, 2019 and 2018, respectively, that was included in the deferred revenue balances at the beginning of the respective period. Professional services revenue recognized in the same period from deferred revenue balances at the beginning of the respective periods was not material.

As of March 31, 2019, approximately $195.7 million of revenue is expected to be recognized from remaining performance obligations for subscription contracts.

The Company expects to recognize revenue on approximately $116.3 million of these remaining performance obligations over the next 12 months, with the balance recognized thereafter.